Need some outside perspectives on this situation

A guy from my college who hurt me pretty badly in the past reached out after almost a year of no meaningful contact. We were in a pretty messy situationship. Back then, he was disrespectful, inconsistent, left me without closure, blocked/unblocked me, interfered in a later relationship of mine out of jealousy, and generally admitted he was selfish and didn't consider my feelings.

The first time he contacted me, he wanted to meet in person to explain himself and apologize. I declined and said if he had something to say, he could say it through text. He apologized briefly and that was it.

Several months later, he contacted me again with a very long message. He admitted that he treated me badly, took me for granted, was immature, jealous, and toxic. He said he's spent the last two years feeling guilty, that he has changed as a person, and that I was one of the main reasons he learned from his mistakes.

During our conversation, I told him I wasn't angry anymore and had moved on. I explained that the experience taught me to stop sacrificing my own peace for people who don't treat me well. He repeatedly apologized, acknowledged specific things he did wrong, and said he wanted me to know he isn't the same person anymore.

What stood out to me is that a lot of what he talked about was his guilt and how much it bothered him that I probably still saw him as the person he used to be. He said he wasn't expecting anything from me and just wanted me to know he'd changed.

By the end, I accepted the apology and told him not to carry the guilt forever, just learn from it. We ended on civil terms.

I kinda feel weirded out cause he has a really nice girlfriend (we were friends before)
I don't think she would be comfortable in him talking to me and I feel guilty like what if she doesn't know he texted me. But when he reached out again I realized I still have a soft spot for him and it made me really uncomfortable so, though we ended on not bad terms I blocked him...but I still gotta see him in class every day for a year.

I don't know what I'm looking for exactly but would appreciate inputs