I dont think you want my opioion on this subject. Youre taboo for this other fella. Your very open for some other fella to take advantage of you at a time when things may not be going well at home. If he was any kind of gentleman, he would back off. he may state how wonderful, and pretty and on and on you are, but he should not cross that line of physical contact....even if you are the one that starts it.
He should say that as long as you are married nothing further can be done. If anything, he should back off and let you and your husband work this out.
You also need to open your eyes. The grass is not always greener on the other side. All marriages are going to have problems, there ups and downs. You cannot just take the easy way out. Maybe this other fella is just a player.....so then you will be divorced and no boyfriend either. You better wake up.