Background
Being around people is tiring for me (the more people, the worse it is, especially if I don't know them well). It also often causes me anxiety. When I'm really too tired, I just want to stay at home and do nothing, but I often feel like I have to go and force myself to do it (even if it makes me unhappy).
What I sometimes do
When I really don't feel like going, I just pick up a lame (but true) excuse and hope the person will not resent me for not coming.
Here are some of the excuses I used in the past:
Sorry, bars make me really uncomfortable.
Sorry, I have other things to do this week-end (do the food shopping which will exhaust me and prevent me from going to the party later).
Question
Lame excuses are lame and I fear people will take it personally (like I don't like them), especially if I do it too often. So, I'm thinking of telling them about my anxiety and my tiredness, but I also fear they will take it personally (my boss did when I told him that talking to him make me anxious). Also, I'm afraid some people will translate "people tired me" as "You are really tiring" (my aunt might be one of those people).
So, how can I tell people (especially my aunt) that I might refuse some of their invitation without them taking it personally?
Notes and clarifications
My aunt is insecure and, since her retirement, she sais things like: "No one come visit me, no one like me".