I really do empathize. I know this may sound unlikely, but it did really help me to have another child, although it took a while for this to "work," obviously. One though on this:
*He is quite cautious in new spaces, and sensitive to sensory input. (And emotionally sensitive in general.) So my attempts to take him to things like group classes haven't really worked out.
Gently: I have know quite a lot of new moms who have had not-great experiences with group outings with their littles and decided to put them off or avoid them for sometimes years. I get the impulse but I advise you to either keep trying, or, if it's as bad as all that, seek help for the issues that are making it so problematic. I do think kids need group time and I also think it's good for mom, too. He will eventually adjust better to preschool and school if he's gotten more of the time, and you will feel better knowing he can handle other environments. Also, do you use babysitters? I avoided them a lot with my first because she was intense and I was afraid to leave her with people. It was a mistake. Find a good one.
I am familiar with that trapped feeling. I am so glad to not be in it anymore. I would say...the world is full of other people and other environments and you don't have to be everything all the time. Take a break, even if you worry that he will be less than happy or that others will find him odd in some way. Lots of kids are odd in some way.
