Re: Can this actually save my marriage, or will I break first
Just motivate yourself to do things that will make you happy or work out. Find friends and family to help with the emotional support.
Who knows, in the end you might not even want her back but the idea is to detach and gain your identity as you again. Also, do not live your life hoping that her affair fails or succeed, the goal is what you need to do to be fulfilled again. In the end, you do not know who she will pick, but also, you may remove yourself as a choice later on as you detach and the bond that drives you to her eventually dissipates away.
Think of love like an addiction. This one currently is bad towards your mental health due to the pain it causes. The more you interact with her, the harder it is to let go. You may fail, but eventually the fire will burn you enough where you will protect yourself against her. The bad news currently, your love or attachment is driving you to reconnect. Love has a level of obsessiveness to it and learning to be mindful when you feel motivated to reconnect.
As of now, she does either not fear losing you, thus she is not motivated to cut off the relationship or she is more in love with the other guy, then you are in second place. Whether she loves him more, or the culmination of his illness and the love she has for him, at present, it is stronger than the motivation she has towards you.
In the end, no relationship is guarantee to last and people change. The hard part may be recognizing that the current her is not the one you want and letting go of the past. When you associate with her, I am sure the past memories come up a lot. It will take time to associate this newer version of her that is before you. She may change or she may head more into the direction that ends the relationship. Again, in the end, the only person that is guarantee to be with you is yourself.
I am such a tree hugger because it gives me wood!