I[28F] was a jerk to my ex[21F], how can I fix this?

I'm not really sure how to start is or what I want from this, could use your advice...

When I was 25, 2 years ago, my ex, Linda, had just broken up with me. I had a history of cheating on girls and for the first time, someone had cheated on me and broken up with me. I was a wreck.

After a few months, my friends told me to get on Tinder to find some girls. That's how I met Michaela, who was 19, turning 20 at the time. We got along great and she was really mature. We slept together and after a week I asked her to be my gf.

For a month, things were great, although Linda kept on texting me, badmouthing Michaela. I don't know why but suddenly I felt trapped. I started to push Michaela away. I told her we would never last cause I was her first gf, that we were supposed to be together for a while since I only had relationships of at least a year.

I also said how I would love her as long as she let me and that if I ever broke up with her I would be doing it at her place. Anyway, due to anxiety, that I had gotten after the breakup with Linda, I was unable to leave the house a lot, but sometimes went to have drinks with Linda still, never with Michaela.

One day I told Michaela about a new friend I had made on Tinder, she got mad. I told her I wanted to meet the girl and Michaela told me to ask her first whatt she wanted from me. After not having done that, we argued and she came over to my place.

I was a jerk. I told her how she was a loser and how, if she wasn't there, I would be having sex with tinder girl,and how I wanted to break-up with her. How I wanted to punch her in the face when I saw her and how everythime she talked about her death parents it made me feel like I could not leave her.

A day later we met up and I told her I'd be only meeting tinder girl for 2 hours, but it became 7, and I did not warn her. She then cried the whole night while I was trying to sleep and after that I went to see Linda.

I then went to Michaela's place and her friends told me I was a shitty gf and I broke up with her.

We never talked again and a few months later I was at a bar with another girl and we kisse in front of Michaela.

I know I was shitty. The girls I dated after her were never like her. Michaela was kind, listened to me, resepcted me, she never pushed me to do things, would often tell me how proud she was.

I ran into her best friend, who told me she hasn"t dated anyone after me. I feel like such a loser and like it is all my fault. Should I reach out to her?

tl;dr: I was a jerk while dating a girl, how to solve?