Because God says practicing homosexuality is wrong (Leviticus 20:13; 1 Corinthians 6:9), this question is focused on how God would have us treat sinners. People generally think that by showing someone concern or kindness, we are somehow condoning their behavior. But this is not always true.

Let's start with the example of Jesus, the only one who has lived a perfect life as a human. People who asked for His help generally received it, even if they were considered "lesser citizens" such as women, foreigners, tax collectors (publicans) or known sinners. Perhaps you've heard people make the statement that we should "hate the sin but love the sinner." This principle is consistent with Christ's example since He never condoned sin and yet was called "a friend of tax collectors and sinners" (Luke 7:34).

Before being crucified, Jesus asked the Father to watch over His followers. He said He did not ask that they be taken out of the world, but that they be protected from evil (John 17:11-16). Later, Paul told the Church members in Corinth that when he wrote to them about not keeping company with sinful members in the hope of encouraging them to change, he was not talking about avoiding sinful people in the world because then they would have to go out of the world (1 Corinthians 5:9-13). He was talking about people practicing sin within the Church.

From these passages we learn that Christians are expected to live in a world that doesn't follow God's instructions and yet not become a part of it by joining in the misconduct. So it's not wrong for you to be around your relative as long as you don't encourage or get involved in that person's wrong behavior (and as long as it is OK with your parents and safe).