Fuzzybear ~ it is a hard pill to swallow, I know. You have to stand up for yourself at some point in life and not let anyone get past your limits.
15 messages per day feels pretty extreme to me. That would definitely make me very uncomfortable, if I were you. I recommend speaking up for yourself (rather than sitting by idly hoping that they'll get your "hint"). Send a message telling them that you are uncomfortable with ____. Please wait for reciprocation of some kind, before continuing with sending more posts to you.
I hope that our ideas have helped you at least feel more comfortable in the way that you're feeling right now. It's okay. You are normal.

Now, you just need to pass on what YOU are comfortable with doing.
((((( hugs ))))))