oh honey. i am so sorry for your troubles. its a hard time for a three year old to go through all of that. but the good thing is she is young. she is confused and doesn't know exactly what is going on. and you as her mother can understand that. just show her extra love and attention, cause this is a hard time for her. and after a while you will see that as time goes by and she gets more comfortable with the new changes in her life, she will calm down.
i understand that you are hurt by your husband, and are still in love with him, but you have to work through this. who really wants to be with a person that doesn't love you? and moving on, and showing your daughter that life is ok, and you can pull yourself through anything will help her in the long run.
i can see how you are struggling with being pregnant by this man who has hurt you so much, but this is not the baby's fault. you are pregnant and this is a joyous time. be grateful that you are now blessed with another child. and yes, times will get hard, and life will be tough, but you will have two beautiful children to go through life with!
i don't know your husband at all, but for someone to leave his pregnant wife and mother of his child for another girl, doesn't seem like much of a man to me. for this i can only say is if i were in your position i would wait and see how he wants to be involved in this pregnancy....and you have the right to name the baby what you want. no body can stop you on that. if he isn't interested in being there to do the things you think he should be there for you with, then that is his decision. you can do this yourself, and you will do just fine. just don't be one of those drama queen crazy women who try and force the men into being there for the baby, that only drives the men away.
and i know you can make it through this, the only hard part of all this is going to be the divorce itself.
good luck.