OP, I'm going to tell you one of the most important things I've ever learned, as it sounds like it may be something you need to hear...the great majority of people have no clue about life, so you shouldn't be very worried about what the average person thinks about you. Especially if you don't know them...they don't know you either, so nearly any judgment they make about you is premature. Remembering this can help you tremendously with your social anxiety.
Of course, it doesn't let you off the hook completely, in that you need to choose friends wisely, listen to good advice, consider who you are and whether that's who you should be, etc. But don't let the fear of strangers thinking you're stranger hold you back from meeting the people who are worth being around, or from being one of those people yourself.
Let go of the it's not an option, it's not a good option, I can't, I won't. Your goal is to be nice, meet some people who also want to be nice, and have some fun and enriching experiences, right? And you are used to your current situation, so trying something new will be challenging, uncomfortable, and maybe even embarrassing, right? But you're not happy in your current situation, so you're willing to deal with that and make some changes, right?
So slip your chain, pop a breath mint, and go for it. Nothing can stop you now.