I agree all of responsers.
Trust is very critical to carry on marriage with a good communication. Currently, my husband with many years has some feelings towards woman who lost her husband one year and a half years ago. I was very furious and confronted after hearing one hour's talk over the phone in the midst of dinner time. At first, he denied vehemently nothing going on. However, I mentioned my hurtful feelings and after two weeks' later, he started talking about conversation with the widow. That talk was good, but I still feel hurt that I told him point blank.
If I were you, I ask your husband the reason why he keep doing 'sexty things' with young girls. If there is no convinsful answer from him, then he has no effort whatever to stop it.
During my difficult time when my husband did not speak about the widow, I worked very hard tending flowers and around the house to keep myself busy not thinking about it, although of course my hurtful feelings was always there. Practically, my principle, 'good moral and 'conscious' in my family was not to alleviate my hurtful feelings but appears to me my husband started to realize 'family is #1,' .... rather making effort with that widow.
Try some good things for the family and also things your husband loves to see, since there is no good conversation to carry on when you upset about it.