My question involves landlord-tenant law in the State of: Florida

I am currently renting an apartment in Florida with 3 others, so 4 people total. After only 4 months into a 15 month lease, one of our roommates decides he wants to go back home to New Jersey. He has already signed a lease with all of us, so all of our names are on the apartment. He has been paying me his portion of rent up until now with no problem (I have been writing the check to the apartment complex from my account) but he now no longer feels he is obligated to continue paying. What are my options in suing him for his portion of rent? would a judge make him pay for all future rent until the lease is up, or do I have to seek out someone to replace him? Who's obligation is it to look for a replacement roommate for his room, his or ours? And if we are unable to find a replacement (since we are mostly new to the area and don't know many people) would we have a case to sue for back rent for all the months we had to compensate for his missing portion of rent?

Another issue is the fact that he has moved out of state to New Jersey. He did not give any notice to the front office about moving out, so legally his address is still here in Florida. Also, his only valid drivers license is in Florida. Would we still be able to file a case in small claims court against him, despite him currently being out of state? This has been a big issue for us seeing as we still have roughly a year left on the lease and are not able to find a replacement for his room. We all feel he is still obligated to pay his portion since he signed the lease.

He is also telling us that he has a great lawyer that can get him out of any and all legal obligation. What, if anything, can a lawyer argue as a reason for him to leave without obligation?