…this is a tough situation… although it is important to accept people the way they are, how your spouse, etc. acts does affect you…Be completely honest with how you feel…but be careful and patient…
She needs to lose weight. Period. However, it not that easy, especially since she has a lot of work to do. She probably has a low self esteem and is afraid of being judged…
Your approach should be one of love and respect, for her, for your son, and for you. What she does affects you all. THis is the single most important aspect…
Practically, exercising and eating right is sadly not convenient in our society…and it is even harder if you have a lot of work and are not passionate about it…
Try small steps.
Cook her meals. Get her out of the house one day and while she is gone fix her meals for the next two days…make it easy for her. See how she responds. If she likes it and id helps, keep doing it…cooking clean might become a family affair…
Walking is easy, and most people underestimate its benefits. She prob does not feel comfortable in the gym…go on daily walks with your son and invite her…if she cannot walk comfortably, them find the easiest thing for her to do.
As far as attitude…have you took her lately how capable she is? Have you told her that she is a beautiful, wonderfully, and fearfully made creature? THat she deserves love nad respect? Tell her that…or write it…reading helps…I suggest something from Jim Rohn…it is simple, practical advice that can open people’s eyes. If she is Christian, then the Bible is essential.
…if after trying in love and patience, doing all that you can, tell her that her behavior is detrimental to herself and others and if she does make an effort, then you will need to leave…it may be a little harsh, but if it gets to that point, that maybe what she needs to hear.