I'm driving myself insane

I was in a relationships which ended 10 months ago and I still think about him every day. When we were together the latter half i was in a dark place and i wasn't the best person to be around at times. I don't think he knew how to handle it and I didnt handle it the best either. He ended it and as time passed i reflected and realised alot of things. I felt more in love with him which sounds so odd. But it was too late. I thought maybe we would reconnect, that he would reach out but he hasn't and now I think he may be seeing someone else and I feel so upset. I feel like if we'd tried again things would have been different. I can't seem to let him go.