Advice or thoughts?

I started dating this guy a few months ago and hes got 3 kids and was with his kids mom for 15 years. They habent been together for over 2 years now. And they dont get along at all. Well he started dating this other woman and she had a baby and she claimed its his so he had a dna test done. Well the last fee days hes just completely shutting me out everything was fantastic we took the kids to sea life and went and did a bunch of things with the kids in the last couple months and we live an hour from each other so wed always talk while were both at work and say i miss you or cant wait to see you in a couple days but in the last week hes been ignoring me and when he does message me its just a few words here and there throughout the day and whwn i try to tell him im here for him and he can talk to me and that i miss him he will just tell me "im dealing with a bunch of shit" hell disregaurd everything i say and just say that. So i told him id just leave him alone cause ive tried for days to get him to talk to me about whats going on. Oh and another thing i borrowed his vehicle the other day and ive tried to give it back that same day and he just tells me to keep it for another day and now im on day 4 with his vehicle.. Guys he has never acted this way with me before and i want to be there for him but hes completly shut me out wont open any of my messages even when it says hes active on facebook. I just dont know what to do... Thoughts? Advice? Thanks. Oh i figured part of whats going on is the kids mom and im assuming about the dna test he had done. (Which by the way he was scared to tell me at first but i assured him it would be okay either way if the baby was his or not and that id be here for him and he was appreciative and that was before he had the dna test done)