Was I being rude?

How long a break did ya have?

Well to be fair, I don't think saying that you had "nothing better to do" is the best way to reintroduce yourself to the group. I mean put yourself in their position, they are probably serious about the sport and are quite dedicated, then you reappear suggesting it's just something to do to fill the time no wonder they were mad

I do sympathise with you though. Sometimes (especially when I'm nervous ) I just say the first thing that comes into my head and then afterwards regret it so much. It's so hard to take back what has already been said

Is there some kind of leader in the group you want to join who you could approach on a one to one level? Without the pressure of other people being present you may find it easier to explain your situation and why you may have appeared rude. Perhaps you could also express your dedication and the fact that you really want to join this group. Other than that, I think you should try and stick it out in the other group until you have proven yourself and are allowed back into the group. Something like this is not worth giving up a sport that you have been doing since the age of 9

Finally, try not to beat yourself up too much about it. Yes you said it but everybody says something that they don't mean at one point in their lives, the best thing to do is to try and move on and make ammends. I'm sure that you can do it