The best way to get over one man is to find another one?

I just left a 4 year relationship 3 months ago and I’m having a hard time moving on. Him and I have 4 kids together and it’s killing me thinking of him and his new girlfriend. Pls give me tips on how to move on. Should I just find someone new? I often find myself texting him outside the kids with NO RESPONSE! I’m falling into a deep depression