In general, verbal agreements with respect to real estate are not enforceable. So, questions regarding the text you reference include asking whether T2 replied back (a text to one without a reply doesn't prove T2 had agreed). Plus, what about a writing with T1 and T3? So, without sitting down, reviewing the original lease, getting some input from Landlord to understand where they are coming from, it's difficult to go beyond stating that the original 2 people who signed the lease as tenants are still on the hook for the lease. From there, if one of the 2 fails to perform, then, if the lease states that the 2 are liable "joint and severally", then yes, the landlord can go after just the one person, although that person could then pursue the other for their share.
Accessing this website or receiving an electronic transmission from Nagle Law Group, P.C., or any specific attorney at Nagle Law Group, P.C., does not create an attorney-client relationship or any other duty on the part of Nagle Law Group, P.C. An attorney-client relationship is only created upon an express agreement with an attorney at Nagle Law Group, P.C.