Should my first cosplay be my last?

Ok, so my friends are gonna do a Melancholy of Haruhi Suzumiya video thing. (kinda like demyx time.) And i didnt really want to do it. But then they kinda pressured me into it and i watched an episode of TMHS and i decided to do it. I bought my costume, i got it, and now the suit jacket is too small. (im Kyon) So, should i spend more money (i already spent 70$ on the costume) to have it altered. Or should i just tell my friend that there's nothing i can do about it and that theyll have to find somebody else. Or should i just tell her that i dont want to do it anymore (i actually dont really) and be truthful? This is would be my first cosplay and im not as interested in it as i was.