Husband’s child support holding me back from seeing dying mother

Long story short, we have the kids 50/50 and still pay 600 a month. It’s a lot but the way we figure is the kids need it when they’re with their mom. We’re okay with it (we also have 3 kids of our own)

So recently found out my mother has stage 4 cancer and doesn’t have much longer to live, a year or less. I’m devastated. I want to move out of state to be with my mom for as long as I can be until she passes. After she passes we will return. If we move out of state to be with my mom, We will have to pay 1,300 a month for child support. We can’t do it. We wouldn’t be able to have a roof over our heads. We were struggling with 600 already. Hubby tried negotiating with ex wife to see if she can come to an agreement under the circumstances and she said no she wants full payment.

So I’m all stressed out and upset. I need to be with my mom. I told hubby he should stay here and that way he can be close with his kids and I need to just go so I don’t have to worry about the court drama and a massive payment right now - I need to just be with my mom. He’s telling me no and if I go without him it’s basically like a divorce and it doesn’t make sense to him.

Basically this is a horrid situation and I’m devastated and I feel like I’m under a ball and chain. Idk what to do.