I understand that feeling - I have moments sometimes when I ponder what would happen if I fell down the stairs and hurt myself really badly. How long would I end up lying there, helpless? And I've noticed throughout my adult life, even though I got my diagnosis only very recently, that there are certain people who feel the need to "coddle" me - which embarrasses me, as I'm uncomfortable with being the focus of other people's fussing.
The only advice I can offer is to try and work on the problem from the other end. Instead of focusing on the difficulties you have understanding your friends, do what you can to ensure that they are not misunderstanding you. With introverted people in general, people easily slip into the assumption that our quietness indicates that we don't really like being around people, or don't enjoy the activities as much as they do. They don't realise that we need to have more personal space and time than they do, or that we can enjoy listening even though we don't say so much. Even with the best of intentions, people sometimes think they are being kind by "playing along" with a falsely perceived need for greater emotional distance.
If you do have to turn down events sometimes, because you just can't handle it at that moment, be careful how you turn down the invitation. People are very prone to generalise your response - that you won't want to do that activity ever, rather than just on this particular occasion. So make sure to let them know that the thought is appreciated, and that quiet nights in are sometimes a necessary part of keeping your emotional batteries charged up.
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When you are fighting an invisible monster, first throw a bucket of paint over it.