The breakup of a marriage is almost always very painful to at least one partner, and you did the right thing by providing a shelter for your son. And I deliberately use the word "shelter," because that's what your home has been for him: a shelter or refuge from life's storms.
You also are right, however, in saying your son needs to get on with his life. But why hasn't it happened? Is it simply because he's lazy, or you have made it too comfortable for him? Or is it something deeper? I don't know the answer to this, of course, but I can't help but suspect that he also is very discouraged, or even depressed. If so, he may need professional help to overcome it. People who are struggling with depression often find it almost impossible to make decisions.
Share your concerns honestly with your son, and urge him to make some clear decisions about his future. If possible, work out some deadlines together when he will begin looking for a job, for example, or finding other housing. Stress that you are insisting on this not because you are rejecting him, but because you love him and want what is best for him.
Most of all, pray for him, and encourage him to seek God's will for his future. God cares about him even more than you do. The Bible says, "The Lord is close to the brokenhearted and saves those who are crushed in spirit" (Psalm 34:18).