omg....please help guys I'm terrified

Ok so recently me an the other half have been arguing quite alot and generally not getting along we have tried to fix things but then something else comes up that requires yet another argument... I suggested splitting up as all this arguing shouting and screaming and stressing isn't good for me or our baby (I'm 28 weeks)...we recently used a mutual friend to mediate a conversation to fix one of our many problems and as far as I was concerned it was sorted. done. moving on. but no. he brings it back up two days later causing yet another debate. I'm tired I want to enjoy the last 3 months of pregnancy... and it gets worse...I have a sneaky feeling by some of the things he has said in arguments and discussions that if we were to split up he would take sole responsibility for our little guy. he's saod things like "if this goes to court ill win"..."Don't think that the baby goes where you go"...he has had me in tears about this and has said he would never take the baby but he can be a nasty if he wants to be and I don't fully know i believe him when he says he wouldn't take the baby from me...cause I know he likes to hit people where it hurts...guys I'm terrified..I can't sleep. it's all I think about...I want to be with him and try and work things out but I also don't want to have to stay with him jist so I can see my child every day...it's my first child im scared... i would never stop him from seeing the baby I'm not that way inclined but I would be willing to come to an agreement where responsibility it's equal...im not sure if I'm reading too much into this but surely as mothers you can understand my fear... I'm not sure on UK law...(I live in Scotland) were not married etc...what do i do? I have nightmares that after I give birth I never get to see my baby.