Tough choice...Do you have any parents to live with, or can you support yourself and the baby? It is very nice of you that you want your child to have a dad but if you stay with a man that you don't love and don't trust, you will only be unhappy and so will your child be. You could try couple therapy....Maybe you can learn to trust each other again and discover that "flame" that was there in the beginning...
But if you can't, than separate. Even if you are not lovers anymore, he can still be a father to your child...And a very good father...It is up to him. Meanwhile you may find someone to love and love you back and this way your baby will have two fathers...It will be hard for the little one to understand what is going on at first but if you manage to communicate well he/she will learn to live with it and get along.
But make sure you don't have several partners because this way the baby will be very confused and is more likely to develop trauma. He/she will need a stable man in his/her little life. It is better without than with man walking in and out on the baby's life. So you will need to be extra careful with whom you choose for a partner and only after you are sure he is the one you should you introduce him to the baby's life.
Try therapy first though...For your baby's sake....It is true it won't die from you and his/her dad being separated but it is a million time better for the baby to have both natural parents with him.
It is your choice and yours alone...But think hard before making it....You now make decisions for two... :)
good luck!