Last month rent / 3 months security deposit

[coucou]

Hi,

I'm leaving in a 2 bedrooms, $3500 / month apartment, my roomate signed the lease last august, I did not, but I am directly paying rent to the landlord. It is a 3 months rent security deposit (10500) and I have $1700 left in the security deposit, the rest being my roomate's and our lease ends the 31st of July. I'm leaving the country on the 31st, and since I am not in the lease, I am not gonna recover directly my deposit before leaving the US, therefore I don't want to pay my share of the last rent, which is equivalent to what's mine in the deposit.
I am planning to discuss it with him, but I wondered if the landlord could retain more than the share I owe and impose penalty for me not paying, even if the rest of the deposit is not mine, and if he still has plenty in stock in case there would be damages (which aren't). Usually I know that he cannot keep more than what is owed (here, it would be half of the rent), but still... do you know what may happen?