Salaam,
Slow down sister, slow down...you have two immature beings and you are being torn apart.
Do not allow your husband and your daughter to put you in the middle of a war. They are winning. They have won. Each gets what they want and you are left with guilt.
First, your daughter is only eleven. Why have you not told her that you are Muslim? She needs to know. You need to respect her in that sense. Let her know why Islam is important to you. I sense an ambivalance in you. You are her mother and it is your duty as a Muslim to raise your daughter, a minor, as one. There is nothing else in this matter. Her world does not make sense to her. Every child wants mommy and daddy back and she is getting close to that. You are the adult. She has no choice. If you give her choices now..by the time she is 15 she will be walking around pregnant. Do not place her in a position that makes her an adult.
By allowing your daughter to make choices you are allowing your daughter to manipulate your marriage. You have placed your husband as a " bad guy". He wants a home that respect his morals and faith.
Sister, do not go to your ex-husbands home. Many of the people who post are very young and naive. Why would you want to expose yourself to this? We try to flee from the influence of the devil. You are running into the devil's playground. No, I am not saying your ex is the devil.
Simply put, you need to take charge. You need to become the adult and let her know how your home is. This will make her life easier. Why would you allow your daughter to be with the kuffir?
I do not expect you to like what I have written. But, please think about it. There does not need to be polarization here. Your daughter has been very effective. Show her Islam. Your ex is nowhere. Slow down and think it through.