Kimmy... I COMPLETELY UNDERSTAND how you FELT!
I have been there. OH! Have I been there. I use to ride with my tri club, and I would be the last one... and eventually I would be dropped. One day I was so far behind, and riding alone... and I was just wondering what the hell was I doing out there? I wasn't getting any better and I was too damn slow.
Lately I have also been frustrated, because I am in between groups. I am a tab bit too fast for the 14-16 mph group and too slow for the 18-20 mph group. I want a challenge, but I also don't want to ride alone or keep someone from having their ride, because they have to pull me in.
Not to mention... everyone I start to ride with... gets faster than I do, and I lose my riding partners.
I talked to my tri coach about it, and he told me that I need to:
1) Work on intervals.
2) Ride with faster groups and be OK with being dropped (this means I have to know the route).
3) Do some weights in the gym.
4) Do some hill work.
So, I have started doing that.
Look... you can get better... with some hard work, pain and sweat. And maybe you ride with the fast group again, know the route and be OK with being dropped... and let the BOP leader know that you will be fine.
Each week you will get a little closer to the group and not being dropped. But yea, you are going to have to mentally strong until you can keep up the entire distance.
I wish you the best of luck... and again, I totally understand where you are coming from. I have been there and in fact, I'm there right now!
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather, to skid in broadside thoroughly used-up, totally worn out, and loudly proclaiming: WOW WHAT A RIDE!!!!"