What do you think of missing someone so much that I'd let him use my body just to talk to him?
Why would you let someone use your body just to get close? You are not a hooker.
It's because I love them so much
It is understandable that you miss someone who you love and want to talk to them by any means. But it is wrong to let others use your body for this. It is unhealthy and harmful to you.
Even if I'm sick and dying, I would let it happen if this is what the person wants from me.
You are wise enough to know better, and you shouldn't let him use your body like that. He has manipulated you to a point where you think you need him, but you actually do not, and it would be smart if you let go of him because he is not good for you. It's important to have self-respect and confidence.