I’m scared of being replaced and I feel alone

I could have written this. Every word of it. I also believe myself to be on the spectrum, and have been encouraged to get tested by mental health providers previously but have yet to follow through. It is exceptionally hard for me to connect with people but I do seem to connect better with people of the opposite sex. This is proving problematic though because I am a bit much to be around most days, and with my constant anxiety and questions and paranoid ideas. My best friend is seeing someone and I have been unenthusiastic about is as I can’t shake the intrusive thoughts that he will harm her and things of the sort and have also been jealous, because I worry that the more time she spends with other people the more she will understand I am lacking in so many ways. I discussed this but in my typical fashion I did it in the most socially inept way possible causing her to block my number because for one she knows I’m incapable of letting things be and I would have spent the next day or two asking silly questions and I also worry she misinterpreted my concern as a desire to be in a romantic relationship which is totally reasonable in hindsight but I’m getting off base here I think. I hit the comment button because it made me feel a bit less hopeless seeing someone else having such similar problems, in a specific way. Perhaps knowing that might help you some way? Maybe not. I hope nothing here comes off as inappropriate, I tend be be a bit tone deaf socially so I apologize if that is the case here.