No longer able to care for my turtles anymore- please help, any suggestions?

I have a diamondback terrapin and red eared slider, maybe around 10-15 years old each but I really don't know. They were given to me after their past owner died and I really feel like I'm not able to care for them anymore. I don't have the money or time to give them the life they deserve and it's making me feel really horrible. I've looked at rescues/sanctuaries but I can't find one that is able to take aquatic turtles due to capacity. I just don't know what to do at this point and could really use some help, I just want them to go somewhere that will take good care of them.