I don't know if you made a wrong decision, but before you try to reverse it, I hope you'll take steps to adjust to your new situation and see if you can become settled there.
Instead of focusing on all the things you've lost because of your move, ask God to help you adjust by finding new friends. One way to do this is to become involved in a local church -- one that not only has programs for people your age, but also will help you grow closer to God. God has not abandoned you, and He may have reasons for bringing you there that you haven't yet realized. Ask Him to guide you -- and He will.
When you do, you may be surprised to find others in your church who feel exactly like you do, and who need your friendship and encouragement. Or you may find others in your area who've never had any contact with Christ or a church, and whom God has placed in your path to help and give hope. The Bible tells us to "encourage one another and build each other up" (1 Thessalonians 5:11).
One reason I wanted to reprint your letter is that it points out a fairly common problem: Many people look forward to retirement, but don't really plan for it by considering all it will mean. But these can be some of our best years if we seek God's will and ask Him to use them for His glory.