I don’t know what to do about my friends

I’m still in high school and I had a boy friend (mind that fact that I now know I’m a lesbian). When I broke up with him it was for more than on reason. But now all of my friends are asking why, cause they don’t know what he acts like when he’s in relationships. But I’m having a hard time saying to the fact. “I’m gay and I didn’t know until after the while I was dating him” but I also don’t want to seem like a jerk, cause they would say I just used him to get stuff out of him... I stayed with him for a month, and waited after Valentine’s Day, cause I didn’t want to be one of those people. But then he got me a huge bear, you know... Then I felt like even more a dick, because I meant so much to him... I just don’t know how to explain this to my friends...