I was in a very similar situation about 4 yrs ago, and it was very tough at first i know it’s a cliche but times a good healer, I did what the others suggested went on some dates went out with my mates just generally did what I wanted to do. But we have a young child and I never talked badly about my ex in front of her made sure I spent as much time as I could with the child,and guess what karma came round and bit her on the arse the guy she went off with and moved in with got a mortgage with was playing around with someone else! 4 yrs later she’s still living at her mums!