How to get over an ex

I dated a guy for a year then one day he randomly broke up with me "to focus on himself" 2 days later he's hanging out witha girl he just hired(he's a manager) and now they're in a relationship and I'm trying to just completely get over him and forget about him but it's hard. I'm trying not to blame myself. It's especially hard cause he has a daughter who I love and she loves me. He didn't even tell her we split just brought the new girl around her and she cried in front of the new girl cause she misses me. How do I get over this guy? He obviously doesn't deserve me