I feel like I don't deserve to exist

TW: sexual themes

A year ago me(21m) and my ex-gf(21f) broke up over something I did.

A little bit of history, me and my gf(now ex) were dating for 2 years before we broke up. Our relationship was wonderful, no fights, no abuse, no arguments. It was healthy and caring relationship, we both were extremely loyal to eachother and we were already talking about marriage and stuff. We were best friends for 2 years before we started dating. So it was a natural progression from friendship to love, that was built on trust.

Our sex life was also really going good, we both were new to it(our first time being in a physical relationship). It was always consensual and soft. We always used to joke about how her "egg" is getting wasted during her periods and laugh about it. We always bring it up during her periods in a joking manner. But it was only a joke. After the first time we had sex(using protection), we both were extremely scared and anxious that she would get pregnant. I even told her that sex isn't worth because of this anxiety we get after having it. But all this aside, one day(the day before the break up), we were casually having a conversation through text. During that she mentioned that she was horny, she was also sick at that time. It was a normal fever. Out of random, I joked that i would do it next time when you're in your periods to save the egg and you can't stop me. She laughed initially and said that that's not how it works sweety. I said i would do it a day before, she said she's not interested and asked me to do it in the bathroom myself. I said "no I don't care". For some reason i didn't realise that I'm making her uncomfortable, and kept repeating "idc" for two more times. I wasn't horny at that time and I had no intentions of actually doing it. I don't really know why I said that without thinking twice, I was just excited that something came to my mind. I just never took her responses as "no" or "stop".

She left the chat and did not talk to me until the next day. I realised what I did was stupid and was scared and felt horrible. The next day she texts me and said she won't feel safe with me and wanted a break. Initially i resisted and begged her telling that it was not my intention and told her it was a joke. But eventually respected her decision and we broke up. I feel so horrible and was drowned in shame. I felt like a monster for causing a girl this trauma. I've always make women feel safe around me, the fact that I did something like this is eating me alive. I feel so guilty and feel like a piece of shit. I've felt like this ever since she left the chat that day. I apologised to her so many times during the break up and after the break up as well, she said she forgives me, but she would never feel safe with me. Which i understand.

I feel like a monster. Past one year has been a hell, i constantly feel like I don't deserve to live and been having suicidal thoughts. I've always hated and critized on criminals who did sexual offences. But I feel like one of them now. Im constantly in anxiety that I caused someone pain due to stupid behaviour. I want her to heal and have a nurturing relationship with someone in future.

I couldn't see myself in the mirror. I want hurt myself and punish myself. I feel like I don't deserve love. I've recently started donating to ngo and teaching kids computer science for free during weekends. But nothing seems to work. I think nothing would make me a worthy person to live. And I'm getting closer day by day to making that decision. It's hard for me to go to therapy too because I'm so scared.