I don't think anything is wrong with advising caution and a great deal of watchfulness.
That's true no matter what gender the ap is, of course.
Makingit, I think the right stuff to focus on is stuff like:
Is your H bi or gay?
If bi, is he willing to be monogamous?
Do you want him back?
Are you both willing to do the work of R?
Clearly, some women enjoy sex with both men and women. Logically, there are men who really are bi and who enjoy sex with both men and women.
Your H is the one who knows best what he likes.
I wish you the best in your attempt to R. If your H is hooked enough on you and if he does the work, I bet your odds of success are about as good as everybody else's.