Need some advice stuck between 2

So my ex and I broke up like a month ago so I started to see this guy from work he treats me good and he's nice to me but he had kids my ex found out by a picture I put about some flowers and know he says he wants to come back and fix things but the new guy is moving to fast and says he loves me and I've only know him for like 8 months but we just started to actually date. What should I do