I went on vacation with my children and when I was gone my fiancé was staying out late at night which he never does.and just before I went on vacation his bank account went from 16000 to -600 . He does have high credit card bills but it makes me very worried. I have caught he online a couple times.he search engine had escorts and I did confront he about it.I trying to save money so I can move out but its sooo hard when I have kids. I went on vacation to spend time with my kids and get away from him . He hurt me so bad I'm hoping after confronting him about what I seen made him stop .I don't know what to think anymore. I trying to buy time but I think he is getting worse.

I would get out asap. You and your children don't need that and sticking around will just make him think he's allowed to treat you like a doormat and he can cheat without you leaving.
Do you have family you can stay with until you can save up to get your own place?

I would be concerned that spending on porn or prostitutes relates to even deeper problems (cheating, the potential of him having a sex addiction or intimacy issue or giving you an STD)

None of the above is likely to change just because you "love" him or are scared of going on your own. Buying time won't make the problem go away. You have to do what is best for you, your kids and moving forward in life NOW.

And he needs counseling.