what to do

my husband and i were at a family function where my ex showed up.he accused me of still sleeping with him .and of knowing he would be there.my ex is friends with my cousin and has been way before he and i got involved.now my husband has been doing off-the-wall things and when i tell him how i feel about it he goes back to my ex...I told my husband I don't want to be with my ex,I stayed around my huband the whole time so he had nothing to worry about .I tell him how much I love and want to be with him everyday so i don't understand why he finds me at fault for my ex showing up where we were.but now we can't even talk without arguing I told him he no longer respects me and he said i didn't respect him when my ex showed up because i didn't say anything.but i found the number of one of his"friends" who is a female and he said that's his friend and he's not going to stop talking to her...then he's started an account on a sex search website and I asked him about it he said so what.we can't talk anymore without arguing,the trust andd communication is gone.I've tried talking to him,even suggest we get counseling and i said if we don't fix our marriage it'll end in divorce.He replied well we can start on it tomorrow..............what do I do?I'm scared he's being unfaithful,at times I don't even think he love me anymore I cry ,at times he laugh .well that happened once,about a week ago.but he's been verrbally,emotionaly and physically abusive.do I stay and try to work things out or do I go.