tryin to sue
There is no tryin to sue, there is only sue or not sue. If you have been served with a summons and complaint, say so.

If the former landlord is only threatening to sue, you can ignore him until he does, or pay what he wants, or negotiate something that you can both live with.

Doesn't the new leases and new tenants void my responsibility to this space?
Depends on the terms and conditions of your lease, which I have not read.

If not, wouldn't they have to show an itemized break down of damages being claimed?
Depends on whether you've been sued or not.

If you have not been sued, you are free to ask for it.

If you have been sued you can obtain that during discovery after you have responded appropriately to the lawsuit.