we recently got back together after 5 months
and he found a new gf.
Is he still seeing another woman at the same time he is supposed to be romantically involved with you? If so, walk away.
You can love someone without liking him/her. You do not have to be a couple to raise your children.
If he has been violent (I will take it that you mean physically), then you should not be together. It is an extremely bad environment to raise children in as is one where the parents are fighting instead of communicating. Do you think your children deserve to see mommy and daddy at each other's throats? Do you think they deserve to be innocent bystanders or targets of misplaced anger and frustration?
IF the two of you are serious about working through your issues and being together, then you should separate and start counseling. Don't get back together until you can control yourselves.
Actually, parenting classes and couple's counseling whether you are a couple or not to help both of you learn to communicate and work together as parents would be a good idea.