yeah, that's not "love."
That stuff is crazy-making, I had that one guy do that to me too. (The one I kept breaking up/going back.) That, "I love you," stuff is disorienting. I wanted to be loved. Really wanted it.
Keep telling/reminding yourself, "That isn't love."
It may be obsession and it's definitely manipulation/fear on his part. Attempts to control.
I actually said to my guy, "Really? You think calling me names and threatening me one minute and then saying 'I love you' the next will somehow magically make me stay? Because it's having the opposite effect." (Or something like that. I may have referenced that I thought he was unbalanced. It was 30 years ago.)
To be fair, I said it from the safety of a phone behind a locked door and he was 20 miles away and he was already on the police radar because I had involved them. I would suggest being as nice and agreeable as you can stomach right now. This could still escalate into more drama than either of you can handle.