You are very confused.

0 sex drive is your own problem. It does not hurt him, unless he is interpreting your 0 sex drive as something that has to do with him. If he is feeling somehow responsible for your 0 sex drive, this problem is solvable by your telling him that you are on medications, depressed, or whatever the reasons are, and making sure that he understands that he has no bearing or influence on those factors. Then it is up to him to decide what to do.

Your being introverted is your intrinsic feature which is neither positive or negative - it is your feature and you have to work with it. If you do not want to be with him because being with him exhausts you, then do no stay with him in order to save your energy, but be honest with yourself - realize that you are not with him because you do not want to exhaust yourself rather than because you do not want to hurt him. He is an adult man who is able to decide for himself whether he wants to spend his time with an introverted woman.

Basically at this time you are messing with your own head, so you are not ready to think about whether you are messing with his head or anybody else's head. You need to work with your own mind at this time.

Not that all of it has any practical utility, other than that in general being less confused would help you be less anxious, under any circumstances.