I don't want to go to the gym with my husband
Is there a specific reason as to why you don't want to go to the gym with your him?
I have bad knees. I have to have surgery so it would be better to wait before going to the gym
Knee pain is the worst and I think that is a very good reason to not go to the gym. Post-surgery, after you recover, it would be great to go, but right now would most likely harm your knees even further. You should only do exercise that protects your knees and a full gym workout is not that.
I don't think it's a good idea to go to the gym so soon after I have the surgery.
Yes, I said that I understand, you shouldn't go to the gym until after the surgery. Tell your husband and he will understand, I'm sure.