Why is it so hard to leave

Why is it so hard to leave such a toxic relationship we’ve been together almost 8 years and I know we’re not good together and it’s a cliche but I love him so fucking much we have a 6 year old son and we lost our daughter when i was pregnant and we just lost our son a month ago while I was 4 and a half months pregnant he just doesn’t respect me and might not always be physical but the emotional abuse hurts so bad today he was just being so disrespectful and don’t get me wrong I’m not an angel I say horrible stuff to him too we’re just toxic but today he was just being so rude and he knows I hate when he calls me a bitch because he just feels like he can and I was talking shit back this all started over me asking him to take the laundry upstairs because like I said I just lost my son 3 weeks ago I shouldn’t even be lifting anything heavy and he started bitching calling me a bitch and I was cramping really bad today so I said fuck you I’ll take it and I was going up the stairs yelling at him and he said oh you must be hormonal your gonna get your period or something and honestly it triggered me because he is so anti women the stuff he says is sick so it pissed me off and said some really evil stuff about some traumatizing stuff he’s been through as a kid but I just don’t care anymore and I went up the stairs and I heard him coming up the stairs and j knew what was next I was like he’s gonna hit me honestly we will hit each other it’s been a while because I was pregnant and he has never treated me as good as he did this last time I was pregnant it’s like I was a god and once I wasn’t I was shit again and once he came up the stairs I was like whatever I’ll just take it expect he had a huge smart water bottle and pulled my hair and was pouring the water into my mouth and nose in a way that I couldn’t breathe I couldn’t scream I couldn’t fight back then he jumped on me and was choking me it was like a life time movie I was reaching around trying to find anything to fight back and when I finally broke loose water was everywhere and I kept slipping falling down I’m so tired of this it’s not like we’re just dating we’re married