What do you do if you are accused of exploitation?

I've been Mom's sole caregiver for more than a decade. I have 2 siblings who have never helped. I have given up everything to care for Mom--my Boyfriend, my home, career, etc. I do it because I love her. . She has dementia, and asked to go several places to have experiences while she can still fully enjoy them. I took her to see her brother, watch her niece graduate from med school, and to visit the place where she was born. What a time she had! I found out so much about her I never knew. She knew of several lucrative opportunities I turned down to care for her. The other 2 kids objected because she has gifted me money. Though I was POA, they picked her up one day, said they were taking her to lunch, took her to a doctor (not hers of 30 years), had her declared incompetent and had my brother appointed temporary guardianship. They said she was being taken good care of and left her in my care, but now I'm going to have to justify every penny I've spent for years. I've been so busy taking care of Mom 24/7; a house that's having all kinds of problems, and trying to keep my health and sanity from going completely downhill, I don't have time to keep track of every expenditure. I keep receipts like any normal person, but don't have receipt for every lunch we've had. The sibs say I don't deserve anything because I live rent free, therefore I'm stealing. My mom says she's generous with me because I gave up the years where I'd making the most income up to care for her. Can someone share who has had a similar experience