Advice on handling being called a "bad father"?

You have no control over your exwife's level of maturity, but you should do everything you can to get her to meet with you to discuss the current issues. You both need to talk about how yours and her relationship is going to affect that little girl in a very HUGE way! Let her know that you both understand that there is nothing intimate between you two and the friendship can be a casual and cordial one. You have to treat her with respect as the Mother of your child and also as a human being and she has to treat you with the same respect as the Father of her child and as a human being. Both of you need to be the mature adults that little girl needs as an example to follow. You don't have to like her Mom and her Mom doesn't have to like You but you do HAVE to treat one another appropriately. Otherwise, I can promise you both you're going to have a disaster on your hands in a few years that neither one of you are going to be able to handle even if you really wanted to! Figure this out NOW...BOTH of you. You owe it to that Daughter of both of yours!