Fiance troubles!! what to do?

my fiance hits me and all that stuff and gets extremely shitty with me over nothing. i am so over it, i want to leave but we have a child and one on the way! he was perfect when we first got together then he slowly got worse, but he started being good again after i told him i would leave if he didnt! now he has decided he is going to be a jerk again!! I have to do everything around the house and aparently our little ones toys are a clutter of the lounge and if anyone come over they would be disgusted! anyone would understand he is a baby he needs to play. i dont know what do to? i want a fun loving relationship with no violence and just for it to be normal like everyone else! please help!!!????