ex over 7 months in just a few days/possibly cheated on me?

Hi guys. I was with my ex for nearly seven months. We started off our relationship as roommates, so we were already pretty close prior to beginning our relationship. Fast forward several months and he's telling me things like "this is the best relationship" and "he doesn't want this to end for such a lomg time." He'd gush about how much he'd love me constantly—my best friend and my partner in one person. We were constantly together. Like, i know that he loved me. Well, we're both moving from our apartment, heading to cities 6 hours from each other. I decided to go on a long vacation before moving. He was debating if we should do LDR, but would sob when we discussed me leaving. He agrees to try it and I go on vacation. About a month into vacation, i decided to buy a ticket back early to surprise him for his birthday. A non-refundable ticket. Six days before I fly out, he calls me and breaks up with me. Tells me this was the best relationship that he ever had, one of the most difficult decisions he's ever made. He's sobbing on the phone, begging for us to stay friends. He said he wanted to end things now while we still loved each other, rather than growing to resent each other. He said that he still loved me, but it hurt too much to say. He promised it was just the distance, but he couldn't do it. I was distraught. I begged him to let me fix things, to let me mend our relationship. I confessed I booked the flight and he is immediately conflicted. But I have to go move out anyways (and $400 is $400.) He said we could talk when I get there.

Two days before I flew out, he sent me a text after next to no communication. He said he was keeping to himself but he still wanted to say goodbye. He said he wasn't going to try anything romantic and that he was doing fine and felt nothing about the situation. Mind you, this is the man who called me two days before we broke up just to fawn over how pretty, lovely, funny, and wonderful I was.

When I finally got to the apartment, everything had changed. I feel now is a good time to mention my ex has BPD. I try to help out where I can, but I still don't understand entirely. At this point, it has been a week. He's removed me from several of his apps, his stories, his close friends. When I get there, I am inconsolable. I tried to keep my composure, but seeing him made it real. It was like talking to a stranger. There was no warmth in his eyes, no care. They were so distant and cold. It was like the seven months never existed. Seven months of knocking on my door and crawling into my bed when he was upset, seven months of sitting outside and talking each other's ear off until 5 in the morning, seven months of him carrying me to bed and wrapping me in blankets and kissing me on the forehead whenever I was tired and unwell. Seven months gone. In just a few days. When he hugged me, he was so cold. And I used to love his hugs, i know them so well. He didn't really seem eager to talk to me and couldn't understand why I was so heartbroken. He said the LDR wouldn't have worked out—it would've become too stressful. He said if we went long distance, he would've probably cheated on me. "It's natural," he said. "Happens in most long distance relationships." I sobbed even harder. He told me that our relationship was good, but he couldn't really care about me romantically anymore—he said he didn't feel anything when he looked at me. He didn't see the girl he would smother with kisses until 4 am, or the girl he held when she got too drunk, or the girl he held close after a trip to the ER. He told me he felt nothing. In just a few days. That was all it took. I confronted him about why he removed me from everything if he wanted to still be friends, and he told me that it was because he was "posting things I didn't need to see." He removed his other close friend, one of my best friends, from his story. He continued to tell me that he really was fine. He'd stayed busy since we broke up, threw parties, went to the park. He told me he had so many plans—taught himself to skate in 2 days. He said that's why he thought he was fine. He said he knew this relationship wasn't going to last. He was "going to be with people like him" and needed "a clean slate without any ties to this place." And that included me. He confessed to me that he was a touch manic, but that it wasn't impacting him now, that he truly was over me. After an hour of listening to me sob, he retreated to his room. "I need to set boundaries. This is a lot for me." And I, foolish enough to believe he felt anything, begged him to stay. I didn't want to be alone. And he slipped into his room and shut the door.

I found out the next evening that he was talking to another girl the evening we broke up and met up with the day after and told a bunch of our mutual friends. friends told me that he told them a day after we broke up. i called my ex about it and he said that it was normal and he was sad and he couldn't be sad anymore. he said it was normal to rebound. i have a feeling he was cheating, even if he swears he didn't.