I say confront, but you have to put professionalism and 'delikadeza' in confronting her.. even if you might think dili nimo cya ka level but you still have to.
big robbery came from petty miscellaneous ones before. Stop the mole hill before it becomes a mountain.
I agree with XoXo.. ayaw dayon padalos dalos..
It is really your husband who you should confront first.. After all, he's the instigator in all of these.
if you had done tallking with your husband, then the best you would do is to secondly, level with the mistress. Mistresses often or not exist because they can give moreover sexual libidos that husband's are having hard time looking for in their wives. Mostly mistresses fills the gap on whatever wives are lackof..
But no matter what are the reasons of your husband's infidelity and whatever outcome it may lead to. Do not sink into self pity and remorse.
There are more single happy people in this world than those who have entered matrimony. You can file a case with your husband and his mistress.. but the stigma and the embarassment it had given to your family cannot be undone already. Whatever it is worth. It will be your children who suffers more.. A Broken family is not something that can be digested by a child right there and then (depende lang pud sa ilang age) but in time they will understand ra.
Pick wisely your decision. Weight things carefully, then put your decisions into actions...