How difficult is it to get guardianship on husband in assisted living with dementia? How long does it take? Could he contest and win?

Dr. has documented his dementia, stating he's not capable of handling financial, legal or important issues. He denies this and argues with dr. Could he revoke the P.O.A. and assign someone else? How would that affect our finances? His family sees him occasionally, believes he could go home. I've been cautioned by dr., sw, nurses, therapists, attorney, friends, neighbors, family that it would destroy me. He has threatened to have sex with me "whether I like it or not". He has made passes at young female employees at A.L., went into a resident's room after shower wearing nothing but his robe (opened)....before dementia, this was never an issue. Age 81, talks about going back to work, applying for a job, has to take care of a multi-million dollar deal (non-existent). Dr. told him no driving. Car insurance was cancelled due to his terrible driving record (accidents). He insists he will drive again. Denies there's anything wrong with him and he "will prove it". His family sees him occasionally and they insist he does not belong in A.L., there's nothing wrong with him and he is normal, even after being told about inappropriate sexual incidents and needs to go home with me so I can take care of him.....he's a problem at A.L. When he met with dr. today, he told him there was a big guy in surgery and he wants to invite him, the dr. and the rest of them in surgery to "come out and have a drink with me". He now says the only solution is divorce (neither of us could survive individually if finances were split). Then he says he could move out of A.L. (beautiful place, very homey, which he calls a "hole") and live on his own. He's not much of a drinker, but insists he could have a beer every 3 hrs.some evening, even though he's on aricept, ativan, zoloft, and various other precritption meds. I told him meds and alcohol don't mix, it would be dangerous. He stated he needs to hear that from someone with some "smarts". I've tried so hard to help him understand, but no luck, apparently he's incapable of understanding. He's been told about the passes at girls, etc., but denies it. A relative took him to a bank and denied it, said she did not know it was a bank. He withdrew some money, don't know what he did with it. Please .. someone .. what do I do. I don't sleep, feel mentally and physically sick.