Question about Tri Clubs...

I started training on my own late last summer for an April Sprint - Seriously from ground zero and I decided I needed some club/group to help with motivation and obviously to provide experience advise, etc. Tonight was my first night and it was a group run (Ugh!)...it was a little cool out and just finishing the couch to 5k program 2 weeks ago - add a week off due to holidays and a move...over 4 miles...well - it hurt. I had to walk - and I was the last one in...Not shocking - i'm a slow runner - but i'm not sure what I should do from here. I know working out with someone more advanced is helpful, however, I felt like I was holding one person back from keeping up with the group because it was dark out - and he didn't want me to run alone. I was under the impression the group was for all levels, but it appears that I AM the beginner 'level' and i'm not sure what to do with that! Should I keep going and holding someone back on the run? Should I keep rolling on the treadmill alone until I can take it up a notch and have a better attempt at keeping up? Tomorrow morning is the swim group...I hope that my time in the pool makes that event a bit better than tonight's run!!! Any advise would be appreciated!!!