To be honest, it may not be clear at the time if we’re actually helping someone or if they’re just taking advantage of us. Not everyone wants to change; some people only want to stay the way they are.
But what is clear is that they have a need, and God has put them across our path to do what we can to help them. Jesus once healed 10 lepers but only one came back to thank Him; the others were simply taking advantage of Him (see Luke 17:11-18). But did that mean Jesus shouldn’t have bothered with them? No, of course not; one man was changed, both in body and in soul.
At the same time, your cousin is on a dead-end road, and simply providing her with food and shelter isn’t solving her problem. She needs help, and you are in the best position to get her to it; she won’t find it on her own. Ask your pastor, doctor, or other knowledgeable person what resources are available in your community to help her—and then give her a deadline to get connected to them. You’ve probably heard the expression “tough love,” and the time has come for you to practice it—both for her sake and yours.
Most of all, pray for her, and ask God to help you point her to Christ. The Bible’s words are true: “God is our refuge and strength, an ever-present help in trouble” (Psalm 46:1).