Paying back MIL

So earlier I created a post about my husband and I owing his mom some money. I need advice on what to do because I desperately want to pay her back. We don’t have a good relationship because of some things that was said on her end, but that doesn’t change the fact that we owe her this money. I want to come up with a payment plan to pay my MIL, but my husband doesn’t. He’s not interested in paying her right now. We’re trying to save up for a house, and I’m a sahm, so we’re on one income. My husband wants us to save for a house, buy it, THEN start to pay his mom back. He says she doesn’t need it, but that doesn’t matter to me. Whether she needs it or not it’s our obligation to give it to her.

Now here’s another issue, a big issue. We owe her around $15,000, but we don’t know how much she wants. She keeps changing the number. First we agreed on paying back $3,000, now she wants $10,000. The numbers keep changing, but I think it’s just best if we give her all of it, or else the numbers will keep changing, and problems will keep coming up.

How do I get my husband on board to pay her back? He wants to wait until we buy a house, but I DON’T! I want to pay her now. What should I do?

Edit: My reasoning for wanting to pay her back so soon is because sometimes she’ll ask for it, and sometimes she’ll say don’t worry about it. It’s a never ending cycle. She has even gone as far as throwing it in our faces. I feel like we just need to be done with this.