Well, you didn't help that much in that war, at least no more times that the times I went to Tau 23 to assist you guys, but, it's fine, if you want to break the alliance, it's your choise.
What I should remind you is, that you are forgetting someone else here, someone who you have not talked to, Lotek. Before making any choise, you should discuss things with him. Not for RP, but OORPly, he deserves it.