Yes, I did pay last month's rent. The issue stemmed from my refusal to sign the Addendum, because it did not include my current roommate, who paid her rent, with money orders addressed to the management company. I just didn't want to be held responsible the entire apartment, when another person was also living in the apartment. Today, I simply asked her, if we could revise the Addendum to include the current roommate, since she failed to add her to the lease this past month. She said we were beyond that point and that she was filing an eviction. The leasing manager made it clear she did not want to add the new roommate to lease, since there were some issues. Nothing illegal occurred on our behalf. The building manager changed the locks & the roommate called the police. Nonetheless, the roommate paid her rent to the property management company and they are now refusing to add her to the lease. I simply want to move, get my deposit, and avoid an eviction on my record.
Also, I sent my 30 day notice to move a week ago. Aside from hiring an attorney, what else can I do?

On the 3-day notice, it should say the basis of the notice. What does it say? Call up your landlord, ask them the basis for the 3-day notice. Tell them that you believe the 3-day notice to be baseless and malicious. If it is not withdrawn, or if they file a Summons and Complaint, you will be forced to hire an attorney and to seek all legal remedies available against them. If that doesn't dissuade them from filing a complaint against you, hire an attorney.