Am I a terrible person?

So when school sytarted this year I met a guy who I became best friends with but little did I know he really, really liked me. So as the year went on and like a few months ago him and I were hanging out and my friend thought he was cute and so she decided they were dating. He thought I was a joke becasue they met that day but it wasnt. He tried to push his feelings for me aside becasue he thought it would never happen with us. He wanted the next best thing to me. I got a little jealous but I didn't realize I liked him for a few weeks. He started to be a good boyfriend to her and then he started to get annoyed with her and she started to like other guys. I didn't flirt with him but we grew closer, like at lunch he came and sat with my friends at lunch and he would ask me to hangout with him and his friends. He started to ignore his girlfriend and I started to try to back off. I also did like him so i did things without thinking like asking for hugs and stuff. He broke up with her a few days ago and I backed off and the next day she had a new crush. I waited almost a week and I tried to wait longer but we hungout alone and we kissed and I told him I liked him and he said he liked me too and then we started dating. She started dating her crush the same day and I didnt tell her, or anyone right away. I told her and she got super upset and thinks he cheated on her but during her relationship the most we did was hug and he flirted with me more than I did with him. My friends even said that they thought we were either dating or we were going to date soon. She also is upset because he wasn't a great boyfriend but at the same time it was because he was in love with me. He even went to me ex and asked him if he would be mad if he dated one of his ex's (aka me) and he said sure. He did this in the middle of winter, so he planned on dating me for a while. I know we should have waited longer and I feel bad I was the casue of their issues but I didn't know it was me until I started to notice everything. I tried my best to back off but they didn't seem to care about eachother anymore. She started to like his best friend while she was dating him!! I feel bad now but like even some of her friends don't think it was right to be that upset becasue she has a new boyfriend and some are happy for me. Everyone admits I am a better match and he regrets dating her but he didnt want to hurt her by saying I thought it was a joke. I feel bad we didnt wait longer but I really liked him and we are happy together and I don't see why she wants to punch me. I can't explain why he was being a jerk to her while they were dating becasue she would hate me even more. I just want to know if I am a terrible person for doing that or not?