Ex or no

me and my ex broke up a month ago, we were together for 2 years, had our ups and downs, he has a lot he's going through right now so we broke up to get some distance and so he can figure out his life, I randomly met this guy two weeks ago and he's amazing, he's sweet and handsome and I like him a lot, but me and my ex still talk and I don't know what to do. Leave my ex forever to be with this new guy or leave the new guy to be with the guy who I was gonna marry. HELP my feelings and thoughts are lost