Lesbian Relationship Challenges Support Group
This community is for those who are in a gay marriage, and the unique challenges that may be had in a same-sex relationship. Find support and talk to others in a same-sex marriage, and get advice from the experiences of other members.
First, I would revisit your statement of "being 100% straight" because apparently that isn't the case at the moment.
Second, you are young and experimenting is part of life and it doesn't mean you are bad, or dirty it means you are finding your own path.
My biggest issue is with not calling it what it is honestly. The heat of the moment can indeed feel unstopable, but you can always make the choice to stop. If you want to maintain the friendship, tell her you will not go there again. Your are giving her mixed messages right now so she is just as confused. Its your choice, how to mange your life, always has been.