<human>: Provide a brief overview of the text.

My boyfriend and I have been together for three years, lived together for two years, and we had what I thought was a happy life together. We had our normal share of ups and downs until I found out a year ago that he'd been cheating on me with a friend of his. I'd never met this woman, but I knew they were friends from Facebook and Instagram. 

I was devastated, he begged forgiveness, we almost broke up, we didn't, things are sort of better. The point is, we're still together, and I'm determined to keep it that way. I made him take her off Instagram/Facebook/Twitter when I found out, and he promised never to contact her again. I believe he's held up to that, but the problem is that I am obsessed with her social media now. I can't stop ~~checking out~~ stalking her social media.  I am so angry at this woman, I hate her for what she did to our relationship, but I can't stop wondering about her, her life, why my boyfriend had an affair with her. She's in what looks to be a happy relationship now and it makes me so angry that I literally see red.  My relationship is still healing from the horror she brought on us and there she is, happy and in love and I hate it. It's gotten to the point where I check her social media every day and it ruins my mood when I see a picture or a status where she looks or sounds happy. I usually end up yelling at my boyfriend for something stupid because I'm so angry about this woman. 

I know this is unhealthy and it's got to stop but I don't know how to do it. I don't know if I should talk to my boyfriend about it (he's never told me much about her and I never asked much because I didn't want to know), if I should somehow confront her to find out her side of the story or what, but something has to change because this is ruining my life.
<bot>: My boyfriend had an affair. Now I'm obsessed with his ex-mistress's social media/life and it's making me crazy.