I think I might owe the debt I am being sued on, so should I just pay them the money or try to defend against the lawsuit?

It depends on the particular facts of your case. Keep in mind, though, that there are a lot of good reasons to at least consult with an attorney about defending against the lawsuit, and if it is a very old debt or a debt that you do not recognize, whether you should make any sort of payment arrangements at all. For example, the legal timeframe for the debt collector to collect on a debt may be up, and giving a payment, even a small payment, may start the timeframe again. Not defending the lawsuit and just ignoring it allows the debt collector to get an immediate default judgment, whereas defending the case puts it “at issue” and requires the debt collector to present evidence that shows he is legally entitled to be paid for this debt. Defending the case may also make it possible to negotiate a favorable settlement, whereas allowing a default judgment to be entered against you leaves you with very little negotiating power.