She is tickle truthing you with the no sex part.

You already know she fucked him.

The good news is that she saw the value of a dedicated and loving man. An affair is about easy desire, ideals, and lust. Your wife was disease free and available. He dropped her like a rock when she got cancer because she was going to probably loose her breasts, become bald, sickly pale, and weak. She would need care. It would be hard. She would never be as attractive again. He didn't want hard, he wanted easy. So did she, or so she thought.

When shit hit the fan, the only real man (you) came through and cared for her like you promised.

Her scenario is the nightmare of many cheaters. She was at the mercy of someone she betrayed. Fortunately for her, you didn't find out until after she regained her health. Woe to her if you had found out while she was in the middle of her treatment and at her weakest.

Now the question is whether you can forgive her.

To put it another way: if you get cancer (lets say prostate), do you think she will do for you what you did for her? Do you really want to put yourself at the mercy of someone who already betrayed you once? Whose to say she won't leave you when you are in the middle of chemo and at your weakest? Do you want to have lingering doubts that she would abandon you?

I know I wouldn't. But some people find it in themselves and their relationship to 'forgive'. Some report the relationship grows 'stronger'.

It is a minority. I still have my doubts as to those those anecdotal stories.

This is more for the /r/survivinginfidelity subreddit now.