<human>: I'm a girl in my early twenties who's been dating a man in his mid-twenties for around two months. We're in a very temporary LDR, but we've seen each other regularly over the summer and have managed to become even closer despite the distance. We communicate well and never fight, we're extremely compatible, and the sex is mutually mind-blowing. 

The only problem that I have is reconciling myself with his last relationship. I've have a decent amount of experience playing the field, but I've never been in a mature long-term relationship before. He on the other hand dated a girl for five years when he was an undergrad. Their relationship soured a few years in, and from his accounts she became very paranoid and controlling, ie the classic "crazy girl." 

He very obviously adores me and has made it clear that he wants nothing to do with her. Nevertheless, a part of me is intimidated by the fact that she was his first sexual partner, his first love, etc. Even if their relationship seemed pretty bad for a large chunk of it, they were still together for a long, long time. They've been broken up for a few years and have also been FWBs after the breakup (he called it off when he realized that she wanted to get back together). She also goes to the same school that we do, and lives in the same apartment complex as him (it's a huge building that many students live in), so she's a little bit too proximate for me to easily put her out of mind. 

Reddit, please offer me some perspective. I know I shouldn't be bothered by this, but I am, and I would really appreciate some insight to help me not feel this way. He and I have talked about this, but I still feel uneasy about their past relationship sometimes. I know that I can't change the past and what he did then has no bearing upon his feelings towards me, but I can't even conceive of being in a relationship as intense and long as his was. I imagine time is what I really need, but any advice for the present would be much welcomed.

Can you provide a brief rundown of the text in within 3 sentences?
<bot>: I'm intimidated by the length and seriousness of my boyfriend's last relationship. This is silly, and I don't want to feel this way.