She's in a relationship but has feelings for me?

i still love my ex but im doing her a favor by covering up my feelings so she doesnt go and do something wreckless like ruin her relationship. shes been in one for 2 years now and he makes her happy and vice versa. the last thing i would want is to confuse things for her. but now she has feelings for me again and she leaves me little subtle messages through facebook statuses and twitter updates. its not too obvious where her bf would suspect anything but im picking up the hints bcos its little reminders of the things we used to do together. her bf and friends are completely clueless; its kind of like a little unspoken bond between both of us. what do i do?