I'm worried and scared for who my ex has become since his PTSD diagnosis. (TW brief suicidal ideation mention)

TW for brief suicidal ideation mention.

Putting this under the vent tag because it's mainly just one big vent about everything that's been happening, but I'm also looking for some guidance on what's going on and what I can do in this situation. I feel like posting here is probably best because I'm sure some of you will be able to understand what's been going on with my ex a little better and help me with how to approach the situation to help make things better for him. Sorry for all of the spelling/grammar errors, I wrote this while not in the best state of mind.

My now ex and I broke up yesterday after I expressed how upset I was over him losing interest in me. He told me that I make him sad whenever I'm "like this" and that he had to do what was best for his happiness and break up with me. For some background, I am diagnosed with PTSD and BPD, while he is diagnosed with Bipolar and only a week ago got diagnosed with PTSD.

I had gone on a trip to Japan three weeks ago, and before my trip, my ex was all over me. He was telling me how much he loved me, how badly he'll miss me, how he didn't want me to go, etc. We also at that point had been talking about marriage, children, and moving in together by that time next year. During my trip to Japan, he started taking a turn. I had called him my second day there, and he had just started acting really distant and slightly hostile towards me, so I hung up and expressed that to him, which resulted in an arguement where I had told him that I just wouldn't bother him until I was home. He later told me that he had been acting that way because he had a really in-depth talk about trauma with his sister and it had sent him into what I like to call an "episode". I unfortunately know that feeling all too well, so I understood and forgave him, and continued to talk to him for the rest of my trip, albeit less frequently.

After I got home, we immediately got into a fight because he was again being super distant and hostile towards me, and the next day he snapped at me for "always making things worse" especially while he was struggling. I tried to break up with him then, because I genuinely felt awful for how I reacted towards him, and I didn't understand the severity of how he was feeling and doing mentally, but he told me that's not what he wanted and he apologized for the ways he had been acting towards me. The next day we called, and I tried to bring up the fact that he said I "always make things worse" and when he shut down that conversation, I just left because that's the type of thing he had been saying and doing to me for a while, and I was really upset and hurt by it.

I thought we were done at that point, so I blocked him on everything, and went to apologize to him for putting so much emotional pressure on him and making everything worse while he was navigating his newfound PTSD. For the next couple of days, things were "ok". We were talking a lot less, any time I tried to initiate anything romantic or sexual it was shut down, and when we called it was usually silent. There was a day when I was telling him how much I loved him and cared for him and he just straight up muted me, he constantly ignored my messages, and got angry at me when I brought up the fact that he wasn't looking at anything I had sent him on insta, snap, or tiktok. At some point, I don't know when, every time I was with him, he started to just stop asking about me all together. I would ask him about his day, work, friends, what he had been doing, how he was feeling, and how therapy had been, and he'd give dry answers and wouldn't ask anything about me. This really started to hurt me because it felt as if he was starting to abandon me. This made me really sad and depressed, so whenever he needed me emotionally, I couldn't give him everything he needed. This led to a lot more fights and him saying more awful things to me until one day I just snapped and started sobbing and telling him about all the things he was doing that were hurting me, how I felt he didn't care about me any more, and I just kept telling him "I'm done" over and over until I hung up the call because he started yelling at me.

After that, he texted me telling me that I was blaming everything on him and I was getting "all emotional". The only thing that I said that he cared about was that I had allegedly said something false, which it wasn't. Later, we called and he ended up yelling at me, which sent me into an episode, and he denied yelling at me at all, which really stung. A few days later he apologized for things being so hard between us, to which I asked him about why he had stopped caring for me. He told me that talking to me has been hard because I've been "insistent on acting like things are normal", which I have no clue where he pulled that put from because we had just been fighting nonstop and never once did I try to turn things back to normal. I told him that I was trying to act like things were at least ok, because that's what I though would best help alleviate some of the stress he was going through. I also told him that he'd been seriously hurting me and I hadn't really brought it up because I didn't want him to get mad or leave me (which are things he's done in the past). He jumped straight into calling me selfish, told me I had been acting callous, and for the first time opened up to me about what was going on in his therapy. He told me that he had to face the person who contributed to his PTSD almost every day in therapy, which as emotionally exhausting him and I'll I've been doing is making things much worse, as per usual. He also got upset at me for bringing up how my period has been affecting me mentally despite him knowing that my period makes me heavily depressed and suicidal. I told him honestly that I didn't know what he wanted from me or how I could help him because he had been shutting me out and hadn't told me anything about his therapy up until that point. I told him how I'd been there for him every single day, asking about how things were going, telling him how much I loved him, constantly reminding him that I was there for him if he needed anything, and how I've been more than accommodating to his feelings, despite how he'd been treating me. Then, he straight up told me that he "didn't care about any of the bs" and told me that I was complaining about him not asking about my day while he was going through the hardest week of his life. I reiterated that he hadn't told me a single thing about what had been going on, I told him that I wasn't asking him to act like everything was OK and I just needed some kindness, and I told him that the way he treated me really affected how much I was able to help him. I told him that I was done and didn't want to be his emotional punching bag anymore and admitted that I hadn't been perfect, but I also brought up the fact that, unlike him, I hadn't been putting him down every single day and I genuinely had taken an interest into what was going on in his life, and brought up that he is my top priority. He responded to me telling me that he needed to be alone and emotionless, while I needed the opposite, and apologized for the stuff he had said and done.

We called the next day and after a bit in call, he told me that I was making him sad and he wanted to leave, so he did. This broke me, so I called him back and begged him to just be there for me for that night, to which he said "can I go now?" and when I asked him "why is being here for me such a chore for you" he just left the call without saying anything and texted me telling me that we were done and all I do is make him sad. I feel so broke over this. There was so much more he said and did to me that I won't include in this post because then it would be too long and ramble-y, but all of this together is scaring me.

Honestly, I'm terrified for him. I love him more than anything else in the world despite what has happened, and now that he's gone, I'm even more petrified. He went from such a loving, happy guy to someone who I barely know, which I don't think is normal. I don't want to let him go, I want to make sure he's OK because that's all I care about, but I wonder if letting him go is what's best for him. I all I want is for him to heal and be happy, and I want to be there for that, I want to do everything in my power to make sure that will happen, but I don't know if the best way for that to happen is for me to leave him be for good. Another thing, he told me his psychiatrist was putting him on a low dose of an SSRI without a mood stabilizer, which I know from experience is not good for people with Bipolar, and I'm worried that's going to make things 10x worse, but I also know I'm not his psych and that she knows what's best for him. I'm overall just worried sick. I love this man more than anything and I want to help him through this. Please help.

TLDR: My now ex boyfriend, who has Bipolar and was diagnosed with PTSD a week ago, went from an extremely caring, loving, and wonderful person to someone I barely know after he started seeking a PTSD diagnosis. He's been acting awfully towards me, has lost interest in a lot of things, and is just overall being strange. I'm extremely worried, don't know what to say or do, and need advice on how to approach the situation. I'm also worried because they are putting him on a low dose SSRIs without a mood stabilizer. Please help.