Is there a grace period for getting out of a lease in Kansas?

Earlier today I signed a lease for an apartment in Kansas. Originally my boyfriend was supposed to be on the lease with me but his credit is ridiculous and he wasn't accepted. I figured it wouldn't be an issue because he could just live with me and not be on the lease. I went in today and signed the lease and then saw that they had added an addendum to the end of it before I signed (again I noticed it after I signed.) The addendum said that I recognized that my boyfriend was not allowed to live with me and that anyone seen staying at my apartment for longer than seven days was considered a resident. I just need to know if there is any amount of time that is allowed to p before I can void the contract without monetary fallout or credit issues... Please help!