will I be fully responsible for this case if my partner doesn't show up to court?

Showing up does not make you any more or less responsible for the debt. If you do not show up, they will get a default judgement. If you do show up they will still get the judgement, but the judgement willl be on the merits. Unfortunately, since you did guarantee the debt, you are responsible for the full amount, and the creditor can chase after either of you for payment in full. So who ever is working, or has assets will be the easier target. My sugestion is that you get together with the former partner and propose some type of settlement with SYSCO for either a lump sum payment at a reduced amopunt, or payment over time for an agreed upon amount to avoid the judgement and the possibility of forced collection efforts through wage garnishment or freezing your bank accounts, etc. An attorney can be very helpful in negotiating such a settlemnt on your behalf. The only way to avoid payment is to not be working, and not to have acounts or assets they can collect against, or to file for Bankruptcy. A judgement is good for 10 years, so don't ignore the matter.