So, story time. I've been with my boyfriend for three months and we've happily enjoyed our relationship till now. I met him while on a trip with a humanitarian organization we are both members of and we fell in love. Needless to say, everything went smoothly. At least until now.

One week ago I found out he had had a fling with a girl who is also a member of this organization and who had dumped him before we met. My boyfriend told me about her and about the fact that she had started texting him again after a few months and they were now 'friends', and he hadn't told her about me.

I was absolutely livid, but I bit my tongue, because he reassured me that he felt nothing for her. Yet, he told me 'not to hurt her' because that were still friends. Needless to say the thought kept nagging at me.

Two days ago I took part in a trip abroad with the same association and I finally met this girl. My boyfriend kept nagging me about her so I flipped out, and told him that he wasn't being fair, and that he should tell her he had a girlfriend.

He got mad at me, but he complied. The thing is, he told her while we were having dinner, as I was sitting in front of her and this was absolutely embarrassing.

We were both texting him, and he later told me that she had mocked me and that he was a loser for being with me. And of course, she got mad at him for not having told him.

Turns out he basically used me for his own selfish vendetta and I'm absolutely devastated. This girl now hates me to bits and I had a fight with my boyfriend for his disgusting behavior.

I feel like shit right now, and I just want to cry my eyes out because he thinks I'm overreacting and I feel responsible. He believes he was just having his revenge. Any thoughts?