Well, it sounds like your husband is having a full-blown affair.
It's not unheard of... but in general terms, men don't leave their wife and children unless there's another woman waiting in the wings applying pressure.
Your best bet is to educate yourself quickly on the dynamics of the extramarital affair. Books like
Surviving An Affair are a good first step. Marriages can and often do recover from infidelity, but the affair has to END in order for that to happen.
If this is all new, it might turn out that you don't even really want him back. The
knee-jerk reaction is often to try to fix the marriage, but cheaters come in several different flavors. A guy who's a pretty good fellow, but just has his head screwed on backwards is one who's worth the effort. A guy who displays narcissistic tendencies and who consistently feels 'entitled' to whatever he wants is not.
You might give some thought as to what kind of profile your WH (wayward husband) fits before you waste alot of emotional energy on him. It could be that a quick trip to the attorney is a better route depending on your assessment of his
character.
If you're in doubt as to what outcome you'd prefer... you might go ahead and start with the techniques outlined in
Surviving An Affair. You can get a jump on that by typing into your browser...
"what are plan a and plan b, marriagebuilders", and reading the article you find there. Read also the entire Basic Concepts section as well as the HT Survive Infidelity section. My best personal advice to you is to take your advice ONLY from Dr. Harley's written information, and not from any postings you might on his site.