Hey bms, the only options you have are to ignore the feelings and hope they go away (which I doubt they will) or talk to her and explain how you are feeling.
She may not be in love with her current boyfriend, but that doesn't mean she will be willing to leave him if she found out about how you feel. She is clearly staying with him for the sake of their child, and that might not ever change.
I can't offer much advice other than talk to her, but don't get your hopes up and there is a big risk that your friendship will break down once you have admitted you are in love with her. Make sure it's worth the risk.
You could also try and start a new realtionship, once you've found someone else to focus your attention on the feelings towards your friend may change. Good luck with whatever you decide. - xx