My brother, you will be breaking your marriage vow if you dare to sleep with uncle's wife and that will be the beginning of your sorrow.
Also, conscience has already condemned you know that God HIMSELF hates it for it is not legal. The Bible said you should remain and enjoy the wife of your youth and to drink from your own vessel (Poverbs 5:15 - 20). Please don't destroy yourself through the subtle enticement of satan. The woman is a widow and has the right to remarry so my dear don't into that trap.

DON'T sell your destiny nor exchange it for sexual pleasure because when you will realize it will too late and your life, soul and earthly peace would have been gone. Be wise

My sister you are very lucky to have met Christ and satan is not happy that you've escaped hence he moved your pastor to tell your secret to the wife and the wife to the entire congregation thereby disconnecting you from the church where you found Christ. My advice is that you remain in the faith and don't give up. There is nothing God cannot do keep your faith and continue to trust HIM.
What you are going through is normal for anyone that have had deep fellowship with the works of darkness but if you continue with JESUS you will overcome and the light will again shine in your paths. Please look a bible believing church to fellowship because the commands us not to forsake the assembly of ourselves together. You can't grow in the faith and defeat the devil who is very subtle alone. You just have to return back to the church for you protection and growth. Pray and ask the LORD to lead to the church will you can worship.

You life will be whole again as you believe as the Bible say "with our GOD all things are possible". Your uncle and his family will yet accept you and forgive. God cannot fail sister

Great Fashola