I understand this happens and why. However, I only learned of my husbands lifetime of affairs during his Alzheimer's and just a few months before he went to memory care. The sight of him anywhere near another woman even if she is 102 is a huge trigger for me and will send me into a tailspin. His happiness has always been at my expense. Why should that continue?
This type of thing happens more than what people are willing to discuss. Some women are adamant about remaining loyal to this type of behavior even though it is part of the disease process.
We as women are required to give up so much of our autonomy.
Since he is in a facility, I would start picking hobbies to get me out the house. Join a book club, gardening class, cooking classes or anything else that would get your mind off this nonsense. Therapy can help. Personally, I would prefer in person therapy than the teleservice that's being offered. First, it will get you out of the house. Secondly, you can run errands and just be out and about. The key is to get you involved in your own life rhythm again and not be so focused on someone who is slowly losing their memory.
Also, I would cut back on the visits since this interaction is causing you to feel strong emotions once you witness this type of interaction.
I hope you take Scampie's advice in the comments and get a hobby or start joining in some activities with other people to socialize. It's okay for you to start putting yourself first in your own life now. You deserve some personal happiness too. Let your husband and his 102 year-old girlfriend be happy in memory care. Happy as far as that's possible. Keep in mind that he's the one in a "home" not you. You still have life to live and I hope you live it.
Take with a grain of salt what others say (unless there is proof) and take with a grain of salt what someone that has dementia says. Just putting that out there first.
If indeed your husband has had affairs .. or even just 1. I can understand why seeing him with another woman is triggering for you.
You are still in shock. You are deep in grief.
First the fact that you are losing your husband, a man that you have built your life around. to a dying brain.
Second the loss of your marriage. Partly because of the dementia but also to the physical separation and also the knowledge that he was not faithful.
That is a lot to grasp in a short period of time.
Step back. Take a breath. Begin to find yourself. (wow that sounds "new age")
If you are like many you have cared for your husband at home for a while before you made the decision to place him. As a result of that I bet you have not had much time to yourself. So take some time. Book a week away. It could be just a local spot or take a cruise, alone or get a friend to go with. Or go visit someone.
Don't worry about him, he is safe, he is being cared for. If there is an emergency they can get hold of you just let them know how. (I do suggest appointing a temp POA and there is a form for that and the POA can be for a specific time period)
It is time for you to take care of yourself.
You don't have to visit. And I agree, its time to do for yourself. A woman I know started cruising when her husband needed to be placed because of ALZ.
Many residents, visits from loved ones become less and less until they stop all together.
Should the resident then be "alone" for the time they have left?
Sometimes a "new relationship" can also be a part of this next chapter.