It sounds like only your pride is hurt, and obviously you are concerned for your daughter.She is very young and is at an age that will make it easier for her to get over. It sounds like you have been having trouble for some time. No relationship is worth desrtoying yourself for: you have your health to think about and a prolonged problemed relationship will do your daughter no good, even if the guy is her father.
When you are caught up in a situation it is impossible to get things into persective; there is too much emotional trauma going on.In a few years you will look back at this and think about it with a pinch of salt. Meantime give yourself a break, be kind to yourself and love yourself, turn to other relationships for support, but do not encourage negative feedback from other people(this will make things worse), make an effort to be an enjoyable person to be around, and take control of your life, other people can not solve your problems. No one wants to be around a person who is a drain. Love yourself and take the bull by the horns and you will be an inspiration.Have faith is yourself. Every night when you go to bed go over a list of positive things about youself,and positive actions you need to take to get your life back into motion. If one approach does not work then try something else.
Attitude is the key and you will not improve or change it by dwelling on things.IF you think I sound self rightious, let me tell you that I also need to take my own advice and I do understand for this reason that it is easier said than done.