Since my dad died I've been spending every other weekend my mom, my sisters instead of appreciating it, seem to resent it. They feel that I am "enabling mom" and she is using me as a crutch. I feel sorry for Mom she's so lonely after dad's death. It's hurtful that my sisters are condemning me for spending time and organizing things for her. (Like lining up a gardener, a housekeeper, a plumber, taking her to look at independent living, etc. I've done SO much in this past year and I've been happy to do it.) they've accused me of being controlling-- I have no desire to control!! If they would step up and spend a weekend with her I'd be happy to back off.
Or invite them to join you. That way they have a choice. If they don't, then ignore them.
One of my regrets is not spending more time with my Dad after my Mom died. I think that's when he just sort of settled in and became a hermit. I'm just saying that because I've seen what can happen on the flip side. I think what you're doing is awesome!