Guardianship Question?

Man, where do I start? Me and my wife had some friends that started doing drugs. Long story short, their kids got taken away by DSS. Nobody in either side of their family could take the kids due to drugs or criminal backgrounds. DSS asked us to take the kids TEMPORARILY, lasting three months. Just long enough for the parents of the children to complete some programs through DSS, cdv and drug classes. The parents were non-compliant with the programs and DSS asked us to take the kids permanently. We have known the kids since they were born. A 7 year old little girl and a 3 year old boy. The problem is that we can not do it anymore, logically and financially speaking, but we do not want the kids to go to foster care. We have had the kids for one year. They are happy here. The court ordered the parents to pay child support, but they have not paid a dime yet. They are currently 2500 dollars behind and the courts are telling us that it will be another two months before they are ruled into court. Granted, our motivation was never money, but we have had them this whole time with no help. We feel like DSS backed us into a corner. We love the kids very much, but can not continue to do this financially. One more thing, the 3 yr old has some developmental issues due to the mothers drug use during pregnancy. I know that it is not his fault, but it is so difficult taking care of him. My wife had to go on anxiety meds because of the stress. We also have 2 kids. Meanwhile, the mother of the kids is pregnant again by an unknown father and they are living it up, spending money remodling their house and hosting partys. What should we do? Please Help!