I know I royally eff’d up. How can I fix it?

We have my families Christmas party(mom’s side) this weekend. We had decided to stay at my MILs because it’s easy. We live a few hours away. Everyone at her house is sick so I suggest we stay at my sisters. My husband says “that’s nice of (sister)” so we hadn’t 100% decided but she said if we stayed she’d need us to babysit my 3 month old nephew as they have a Christmas party. Her MIL was going to babysit but she’d cancel her. My husband says “we’re probably not headed back Friday night” so I said “ok I’ll tell my sister not to make the bed” and he agrees.

It’s important to note my mom’s going through chemo and trying to not get sick. This morning he says he feels a bit mucky and “can’t you hear it in my voice” his voice sounds hoarser. “Maybe we’ll drive in day of”

I asked him what he wanted to do. He says we should skip staying at her house because this could be nothing but it could turn into something and we don’t want to expose them. Says we’ll play by ear and if he’s feeling better day of we’ll go.

I asked him what to say because I wasn’t sure he says “tell her thank you but we’re gonna drive in Sunday” I say “I wasn’t sure if I should tell them your feeling mucky” he says “no don’t say that” so I tell her verbatim and her last text to me was “that’s silly lol” because she 100% feels hurt that we’re not staying.

Now I realized I should have been honest from the get go and not even asked my husband what to say. Since I asked him I felt like I should respect his wishes I not say he’s feel mucky.

How do I fix this with her?