Hi October,
Hang in there!
I agree with Hoppy. You need to speak up. What he said to you, if he had said it to a person who had not been abused the way you have, would not have had such a negative effect. Yes, he ought to know better. On the other hand, you know yourself and what you need better than anyone, and why not say so to those who are until now clueless!
Yes, it may not be fair. Yes, he might be all wrong. The important thing is to catch the ball you're thrown and run with it. In this case? Tell him that you are very sensitive to being leaned on due to your past and he will need to trust you that he ought not make requests from you, you feel it too much as a burden, or rather, use Hoppy's words, they are better.
Good luck
Plucky