I hope you can find something to keep yourself busy. My FIL used to volunteer at a homeless shelter to serve meals. He loved being able to help others. Once, years ago, I stayed up all night baking five cakes, and delivered them to the shelter the next day. I did it because it made me feel good to give something to the people there. I get my S involved in helping others, too. It makes you feel more confident knowing you have a talent that you can use for others. Walking the shelter animals is a big help to the people there. Even if the people there are younger than you, doesn't mean you can't find some common ground with them, friends of all ages are nice to have.
How is your S doing now? Show him a stronger, more confident mother, and he will begin to gain new respect for you. My S told me when he was about fourteen or fifteen, that he admires me for the way I handled the whole situation with his F, and that he would always remember it. I never put him in the middle of it.
Will your S be with you on July 4th? If so, show him a good, fun time, no mention of ow, and nothing negative about his F. I can understand you wanting to stand for your M, but you can't constantly try to guilt your H into anything, because it works the opposite , obviously. Make an honest change in yourself, become a better you, and get some help for your depression. Find something positive to do each day. Happy Fourth? vc