What can I do

I’ve been 2 months since my boyfriend and I broke up. But I can’t keep going, I feel very down every time wondering why couldn’t avoid my mistakes and today would be a different story. Even I hang out with friends, it’s very hard not to think in him and he looks so happy as he didn’t care. I always take all I feel for me, because people hasn’t been good with me in past. But I can’t, I miss him too much