Help!? What do i do?

Ok, so me and my SO have been together for a while, we have three kids together, about a week ago an "old friend" whom I've never heard of, started messaging him on fb asking how he's doing and talking about her kid she had 6 months ago? Anyways, I was kinda upset, mainly bc hes NEVER OK with me talking to guys or friends or even my ex husband who I have two kids with. Well since then we been arguing, I noticed he changed his fb profile to "single" I asked him about it, buy he swears up and down that he don't know how it happened, then he said it's always been that way (it hasn't). Now he's saying that we're not together!?!! He said he still wants to live together, have sex and all that but he says we're not together but he still loves me? I asked him why would we have sex if we're not together? He said, well, would you rather me bring another girl home? .....are you FUCKING serious? I feel like I'm bout to go to jail for murder for real! He swears it has nothing to do with a female, that it's all because of me because we argue because I ask him questions. Idk how to handle this, and I have NO WHERE to go if I try to leave...