I know how frustrating it can be to have women like that around your husband, it can make you crazy. I just want to say be careful and keep your eyes open. If your husband has been going through a mid life crisis, he may be putting himself in situations that could be potentially harmful to your relationship, and he could do things that are typically out of his character. And with women like that around it's doubly concerning.
I've been there, done that, and am now divorced over it. I'd hate to see anyone go through the same thing.