<human>: Can you give me the gist of the text in a nutshell?

Hey Reddit!

Alright, nuance. I'm currently going out with this great guy, let's call him Aidan. Aidan was good friends with this guy called Brock. I was seriously involved with Brock for almost a year. In fact, he was the one who introduced me to Aidan. Brock however, had a girlfriend at the time we were dating. During the initial stage of our relationship, I didn't know but later he told me and we decided to continue the relationship anyway. 

However, eventually I grew closer to Aidan, and began falling in love with him. My needs of having a stable, secure loving relationship were not being met with Brock for obvious reasons, so I broke it off and began dating Aidan. Things became ugly for a long time between me and Brock. He called constantly, yelling and demanding sex. I refused on the grounds I didn't want to destabilize my new relationship. He said he'd cheated on his girlfriend so why couldn't I. I didn't budge. We broke off contact for a few months.

Recently he got in touch with me again. It makes me feel guilty constantly, he says I treated him very badly and acted selfishly in my own interests without any concern for his feelings, only my own. And he's right, I did (and Aiden's). He is always angry, but in a very passive aggressive way. He asks me to buy him things , like order dinner, and I do sometimes. I need to keep things friendly, because he could absolutely ruin me if he wanted, with the information he has about me. But he is so cold and rude sometimes, and just demands things and though it annoys me incredibly I have no choice but to comply.

Today, he demanded I buy him copies of the books he had lent me during the relationship (we live in different cities now) so I did. He did not do the same for my books and I didn't ask. That makes sense I guess, because I'd be the injured party too if the roles were reversed. I just don't know how to get back to a good relationship (but without much contact!)

Please help, wonderful people of Reddit! :)
<bot>: Currently in relationship with guy A. Ex (B) is good friend of guy A. Ex still texts me and have to play nice because I broke it off and he has compromising pictures and texts from me.