Just a thought ... yes, I am sensitive, too. I get it. But when someone tells me I am "so sensitive" it is usually a slight or put down. It used to hurt me a lot. And I would start beating myself up about it, too.
But the last person that said it to me, knowing her quite well, I refused to take it anymore and remarked, "that is why you are where you are, and I am where I am." (meaning, I would much prefer to be me than a total b**** like you).
She stopped insulting me immediately. In fact, we barely speak now. We both know where we stand.
It is totally unnecessary and uncalled for when someone does not decline an offer graciously. It is their bad. You have a right to feel offended / hurt.
The good news....it has nothing to do with you. You are a good, kind, thoughtful person. That is a good thing. Dont let these idiots get to you. They are lacking. Not you. Time to stop apologizing for extending yourself to others.
Another example, I was super frustrated at work because my counterparts in the NY office were total jerks, with no manners or business etiquette. They definitely had no clue about the Golden Rule. To me, it applies in many instances, even at work. I got so fed up that I stopped making an effort. They are as obnoxious and rude and unprofessional as ever, but I just dont care anymore.
Please try to not be hard on yourself. You are lovely and caring. Whatever the reason, nature / nurture / circumstances. Whatever the case, do what you are comfortable doing, being yourself. If people are s****, shame on them.