Physician here. This is dementia, I’d bet money.
Take her phone. Like physically take the phone. Shut it off- you bought it for her, so you’re on the account, right?
Make her see a doctor (not the ER, but a primary care doc in the office). We can’t fix this, but maybe it will help her gain insight? Or rule out a brain tumor we can treat?
Get an attorney. Buckle up, it’s going to be ugly. I’d take away all of the ways she can reach him. This is not an affair per se, it’s dementia. I would immediately take over everything I could if I were you. Like I’d take credit cards, phones, report her cards stolen. I would empty what’s left of her account behind her back. It would look like I was abusive. She’s not ok. I know that this is painful, and I’m sorry for that. I’m also suggesting some stuff that might be illegal. But she’s not right in the head, and it’s kind of not her fault in a way. Maybe you can make her think he did it, too? Then protect it from her in your account?
That’s does not mean it doesn’t hurt like hell, or that you need to stick around for this shit show. But- Think of this as a psychotic break and you’re keeping her safe. Until things can be stabilized. Alternatively, this will be a shit show as she declines. You can also save yourself and divorce her. Is that an option for you?
This is textbook dementia stuff. Textbook.
My spouse is having issues, too. I get it. Not as bad. Yet. It’s been 25 years of marriage here. I get it.
I would also contact the scammer. Not sure how or what I’d say, but I would. Maybe pretend to be her lawyer or something? This might take a two pronged approach. But she might do it again with another scammer.
I would also manipulate your wife and tell her something about him that would disgust her . Maybe fake a picture of him having sex with another man. Or getting married or having sex with a dog. Whatever would viscerally turn her off. You can get this stuff on the internet or ask an AI bot to do it. There are apps that you can enter in "Make me a picture of Stephen Baldwin kissing a horse with his mouth open while wearing leather pants" and it does it. Google Artifical Intelligence pictures. Usually the apps cost a few bucks.) Might be able to fool her if she has dementia.
Get her kids involved. This affects them, as well.
I’m sorry about your heart issues. I hope your procedure goes well. My husband had an ablation for his afib, too. Two actually. He said it wasn’t too bad.