Your husbands health needs to come first, let them know how hard it is on him to babysit a toddler all day, my husband also babysits his twin three year old granddaughters and it is a lot of work but he loves it, and its his choice my daughter never has expected it.
I remember you mentioning your husbands weight, just wanted to let you know I had weight loss surgery and its the best thing I ever did, no more high blood pressure and I feel great, I went from 270 to 143. Just something to think about for your husband it also cures diabetice in most cases.