Stuck between a rock and a hard place...

So I have been part of a sorority for two and a half years now and only recently began to realize that it doesn't align with my Christian ideals what with it being a secret society and having "secret rituals" and all (not that I took any of these seriously). In fact, I only signed up to be in the sorority because I could not afford any other housing on my campus. Since I only recently realized that due to the rituals and secrecy it is a sin to be involved in it I want to go confess it as soon as possible. The only problem is that I still have to be in the sorority for another few months until I graduate otherwise I won't have any other place to live and won't be able to finish my degree. Would it be wrong to confess it and then not resign my membership for another few months until I graduate? Or does confession call for you to resign such things immediately? On the other hand, I really don't want to wait until I graduate to go to confession... that's four months. I really don't know what to do.
Additionally, I suffer from Religious OCD... so please let me know if it just seems like I am worrying myself over nothing.