You made a huge decision to leave a 25-year marriage and carried out that huge decision for a reason. What's changed? Also, what is the reason? Because what you've said so far doesn't make a lot of sense, to be honest.
You said the main reason you left was that you felt he deserved to be able to have a sexual relationship with someone and you didn't want that with him anymore.
But who would leave a 25 year marriage so their partner can go find a sexual relationship, especially when he doesn't seem to really even want one?
My best guess is "No one."
Older, long-married couples quite often aren't on fire between the sheets, you know. Sex hormone levels drop and other aspects of the relationship usually become more important.
Then you say he only wants you to be happy and that he wants you to move back in so you don't spend your money on rent.
So, he too only thinks about you, not about what he wants?
Really? So you're just a pair of CareBears then.
If it's you or you two's typical habit to be so surface and stick with the story you'd tell distant acquaintances with each other rather than getting real, I can see why this marriage finally broke.
If you want real help with your situation, you will have to explain the actual situation, not gloss it all over.
In any case, this sounds longstanding and complex. Therefore, I'd advise seeing a therapist to sort it all out before you go right back to what you put in so much effort to leave, with no further insight. Good luck with it.