what can you do if you think people are 'alienating' you intentionally

in real life, in society? that is how i have felt for a long time now. like an outcast....i have mental health probs but in the past i have tried to join in social events, but people seem to shun me there, not speak to me, socially exclude me and i felt utterly rejected......so now, i don't really bother...i stay indoors most the time, feeling isolated and alienated.....i have tried with people, but as i said, i've just had a lot of bad experiences, which negatively impacted my self confidence...and i'm now in my late 40s.

my only support mechanism are my elderly mum and dad who live far away, so i feel ' left to it ' here.