Can i sue my roommate for not letting me sign the lease agreement and me paying all of the rent and water

There is no cause of action for you based on the posted facts. Confirm with local counsel.

You certainly can sue your roommate, but there is no guarantee of success on these few facts. Small claims court is likely your best remedy. Check at the county courthouse how to file.

I agree with my colleagues. You may have an argument if your ex falsely represented to you that you were, in fact, made a co-tenant on the lease. Would you not have lived with your ex for over a year had you known from the outset that you were not listed on the lease? Did your ex make any promises to you to reimburse you for at least his 1/2 pro rata share of rent and expenses? Why did your ex pay none of the rent? Was he out of work? Lots of issues to discuss with a private attorney in your area. Experience in landlord/tenant and contract law would be helpful.