I've (38) been alone my entire life and looking for advice

I wanted to start by saying that I've never really been in a relationship in my entire life. Not a serious one anyways. I had "dated" a girl in high-school which consisted of me asking her out, and then her dumping me after week 2. I put dated in quotes because I called her a few times but our relationship had no intimacy.
I tried the bar and club scene like most people throughout my 20's, but never managed more then an awkward drunken kiss. I've always had social anxiety, and this type of interaction is very difficult for me. And now approaching 40, this really isn't my scene anyway.
For a long time, I had just given up, and decided relationships weren't really for me. I could make a go of it alone.. I've been living on my own since I was 18, and never really needed anyone to take care of me. And I do prefer to spend a lot of time alone.
I'm just starting to realize it, but being alone for the last two decades is starting to affect me more and in mostly negative ways. I find myself getting resentful of other couples and displays of affection. And also, do i really want to be alone forever?
As a last panic ditch effort to find someone, I have created profiles on several dating sites, but have yet to even go on a single date, or really even talk to anyone on the platform. Nobody has ever contacted me through them, and I don't have the confidence to reach out. It always happens: Spend hours making profile, stressing over my pics that I hate, trying to fluff up my life to sound more interesting then work > Netflix. Scroll through the lists for a week, then give up and delete the app.
How do I take that first step, when ultimately I don't have any confidence in myself? Probably lower than none. And that's before the awkward "I've never dated or been with anyone" talk that I'm inevitably going to have to give. Compounding that with.. well, how do you even date? Seems like a simple question, but I may as well be the first person traveling to Mars.
I feel like I've trapped myself, and feel frustrated that I cant seem to overcome.
TL;DR - Been alone my entire life and don't know how not to be.
*update: Thank you everyone for the kind words and especially the advice. Based off the majority of reply's here, I have decided to focus less on the relationship part, and more on myself. I have just signed up for some online counselling. Not sure if it will even help, but I think it's clear that I need to talk through some of my anxiety and social issues.


Source.