Hi, this is a very common problem. after my ex and I broke up I was a bit obsessed with her, what she is doing, where she spends time, with whom, and does she think about me the way I think about her. Those thoughts would escalate when I would drink alcohol and then I would find myself texting her. I think what helped me the most was simply time. As time went by I became less and less interested in her until I found someone new and then my interest in her dropped completely. Don't be hard on yourself, time takes its toll.