Toxic co-dependent relationship HELP!!

I know this is long but please give it a read! I'm desperate!!

I've been with this guy for about 4 years now. We had a tew rough spots throughout the years but nothing this bad. Every fight he threatens to kick me out. Every fight he says he doesn't love me or doesn't want to be around me for the rest of the day and then 30 minutes go by and he's trying to cuddle me and saying he wants to marry me. He always says I'll never find anyone better than him or anyone that would put up with me. I've been wanting to leave for about a year now. (I know how terrible that sounds but I'm terrified) He's never hit me but has backed me against walls and screamed in my face as well as punching walls or breaking chairs. I want to leave but l'm scared. I feel like as soon as I leave my world is going to fall apart. Even after the years of emotional abuse I'm terrified to leave. I'm an overly emotional person and he gets angry more than anything.

Yelling scares me but if I tell him that he just yells more and gets upset that I'm scared. This is heavly TOXIC and I DONT KNOW WHY IM STILL HERE. Has anyone been in a similar situation? If so how did you even get half the courage to leave? I am desperate to leave but also absolutely terrified.