Sorry to hear your dilemma, but it isn't too uncommon to hear women vomit lies when it comes to divorce (and all that is at stake). The best thing to do is KEEP CALM. Let her dig her own hole. Provide proof from friends, families, coworkers, clergy, and everyone else how you are not only a good father to your children, but how everything she mentioned were lies fabricated to make you look bad. A *smart* judge will see through her deception and not think kindly of it (you hope).
If you haven't already done so, start documenting EVERYTHING - when she sees the kids, the exact times, when she goes out partying, bank records, phone records, etc. If need be have witness to cooberate your claims. You will probably need them as further evidence.
Again, STAY CALM AND STAY CIVIL. If you don't know by now, you'll soon learn that women have the upper hand when it comes to Family Law issues, so whatever you do don't give her any more fodder.
And find a good divorce attorney. Not some lame POS who is looking to do the least they can for $$$, but someone who will look over the general facts of your case and tell you that s/he will bury your STBX in court.