My Husband is dating a high school student!!!

We were together for 10 years and are still married but separated. I went to get my kids from him yesterday and he tells me about his new 17yr old girlfriend who is still in high school!!! I guess he thought it would make me jealous, but in the long run it only made me want to vomit. He is 29 and sleeping with a 17yr old kid who is still in high school! Hell our oldest is 8years old. I am absolutely disgusted. Neither of then have jobs and this bitch thinks she can parent MY kids. OH HELL NO. I just went and filed for emergency custody of the kiddos and reported him for sleeping with a minor. I have had my kids 2 days now and he hasn't even called to check to see if they are ok.