This is not on his terms... it is yours.
You approach him and talk about it, when you need to/want to/have to. Not according to him or when it is okay for him.
Do not walk on eggshells in other words... he should be the one that is trying to talk about it... to you. He is the one who committed a felony in the marriage... by that I mean a real big problem.
And, you MUST make sure you go to the Doctor, to make sure you do NOT have any sexually transmitted diseases. And, HE must go to the Doctor too, to get tested. His word, is not good enough. It just doesn't cut it.
YOU set the boundaries... for what is expected... he is a Husband. He is doing something vile and disgusting. YOU set the boundaries. He is trolling for women...... like a predator. YOU set the boundaries. YOU set the boundaries. YOU set the boundaries.
Again, HE IS A PREDATOR... upon women and who knows what else.
As for a future.. well he and you I would think, should attend some kind of Therapy or counseling. Gee, look at Tiger Woods and his wife. Gee... ?
Your Husband, is acting like his "hobby" is a sport.
Meanwhile, he still has his wife.... who has put up with him... besides just giving him SA information. What an easy life for him... he can get horny off of other women.. ..but still come home to his wife and family... and just lead them on until someone ends it, or forces him to.
... Um, you should NOT have to wonder about having trouble being "available to him and for him"... he lost that privilege. He should not expect his wife to please him... when he is out hanging his maleness out there to other women.
And if he still expects you to "please" him... how dare he! I would tell him off if that were my Husband. Literally. Don't be afraid to say what you think.
Next, what the HECK did your friend say to him about his sexual pursuit of her??? did she tell you? Is that how you found out?
Sorry to be so blunt.... but unless you both have an open relationship and can do whatever you want without monogamy or trust... then his "hobby" is totally without merit. And... I really hope you do not let this affect your self-worth.
HE is the one... who should be walking on eggshells... for fear of losing his wife and family.
All the best,
Susan