Unless they are the types that deliberately make a mess after you clean up, OR they demand a fresh cooked 3-course meal every single night, you can help yourself by not being so crazy about cooking and cleaning? There are a few things that you can do to minimize your time in the kitchen…
Are your husband and in laws okay with you working? Because I find that men who are okay with their wives working tend to be more relaxed wrt housework…if you are finding ti difficult to handle both (work and home), is it possible for you to cut back your hours or quit work for some time?
Also, about your MIL…being diabetic doesnt mean she’s disabled. Its okay if you dont want her to work and it wouldn’t be wise of you to ask her to help you out but don’t think of her diabetes as an excuse for not doing anything.