Bought a townhouse, but didnt know it was part of an association

I just bought a townhouse and now I just found out that it is in a condo association. There is nothing in any of the sales contracts I signed where it says I would have to pay a monthly fee and abide by all these rules and regulations. Is there anything I can do? Can I sue the seller? Do I have to pay the fee whether I want to or not like taxes? I didn't have a lawyer to help in the purchase. Would it help to get one now? TIA, Warren.