"What happens if my children are there, and they witness that?"
Then they'll see a fight between two people they love. Never fun, but I dont think there's any reason to think it would be damaging per se, at least not moreso than entirely losing a parent figure. My parents didn't fight much when I was growing up. I have plenty of friends whose parents did, and they're ok. My impression is that it's really problematic for kids to witness emotional or physical abuse, but tension or a fight aren't that. That's just my take though, I'm not a child psychologist, I could be wrong about the impact.
For what it's worth, I believe you've been trying hard to do the right thing, and that there is no good solution from where you stand. I'm sorry.