Hi, dear Natasha, i have the best advice for you ,
1. let him play around dont argue with him too much...
2. and dont go for divorce its a hard world to live by ones self and you also have kids ,please dont bring divorce even in your mind.
3. if you are with him he will have to pay all the expenses and in the end his life will be hard (keeping feets in 2 boats) he will realize it .
4. be patient and just let him know that he can do what the **** he wants to but also by doing your thing like always in daily routine make him feel you were there for him always and he also has responsibility for you and his kids , just let him loose he will get it in time .
5, you wont have more demands then his new lover just let him realize it by letting him free to do what ever he wants and in time he will realize it.
FINALLY BY TIME EVERY THING CHANGES AND IF YOU DIVORCE HIM HE WILL BE WINNER AND BY NOT DIVORCING HIM HE WILL BE BOUND TO HIS RESPONSIBILITY'S HE WONT BE FREE,