Asking Stepbrother to Watch Porn Together and Masturbate

My stepbrother and I have always been close, but lately we’ve been getting a little too close for comfort. We’ve been spending a lot of time together watching porn and masturbating, and it’s starting to feel like more than just a hobby. I’m not sure if he’s just trying to get closer to me, or if he’s actually interested in me sexually, but either way I’m not sure how to feel about it.