Joint and several means that you are both obligated to pay the entire amount owed. If he pays nothing, then you are required to pay it all. Restitution is frequently ordered "joint and several" when two or more people work together to commit an offense, and it is permissible for a court to do that. The theory is that the victim should be able to recover the money - even if the amount paid by one offender is more than his "share." You may be able to sue you friend civilly to recoup his portion of the debt. Good luck.
It sounds like the court already answered that: it can, and it did.
You may or may not be able to proceed civilly against your "buddy", but your success or failure will have nothing to do with your civil case.