What the fuck? Am I imagining my presence here?

So a friend of mine from work has an annual party around Octoberfest. Last year I was with my X and in order for other co-workers to not know we were dating we did not go to the party. I suppose I could have left him at home, but I didn't think about that at the time. So this year I was invited again, and with her having recently moved to a job out of town, I wanted a chance to catch up with her. Little did I know what a big deal her party is. Basically, other than her and her boyfriend I knew no-one. Usually it's not a huge deal at a party you can sit on the couch with a drink and get to know some people and join a conversation. Not so much in this case. It was all family and a few work friends from a job previous to where I met her. It was the most awkward 3 hours I've encountered in a long time.

After a couple of hours a second co-worker showed up, and I thought, at last! somebody I can talk to. Yeah, not so much, co-worker #2 had met quite alot of #1's family before. So it was about 45 minutes before #2 made it round to saying hi to me. We hung for a 20 minutes also catching up (co-worker #2 had recently changed departments and works from home most often) and then she decided to leave. I figured I'd take the chance to duck out since I wasn't having fun anyway. So I'm standing there saying good-bye to the host (co-worker #1) with my other friend (co-worker #2) and #1 says to #2 I'm so sad we didn't get to catch up, and then proceeds to invite #2 back over to the house the following day to finish of the food and drinks. I'm standing there, thinking, is it just my imagination or did we not catch up either. I've been standing here for 3 hours feeling awkward at your party, and got to talk to you for all of 2 minutes. So I just stand there with a fake smile plastered to my face while they make plans. Then #1 turns to me and asks if I want my tupperware back now or when she stops in to the old workplace on monday (because, yes, I was polite enough to come over with something for the party).

I thought I was invisible before, but now I realize that I'm really just a doormat. What is the point of making friends, or being nice to people, when they don't give a shit about you really? Am I secretly unlikable? Why do I get the invite to the gianormous party, but not to hang out with the people that I actually do know? Apparently these people aren't as good of friends as I thought. It makes me wonder why I even bother.