Don't wait. Tell your fiance what is happening now. You will never get what you want by lying.
Every moment you wait, especially considering that your feelings for T are genuine, is another lie poised to come back and bite you in the ass. Face it.
There is nothing else to do if you love and respect yourself and the ones closest to you.
It's all going to be hard. Everything is hard. Give yourself a chance in hell and be honest.
"Rocks will open and make a way for the lover."
~Hazrat Inayat Khan
I love Catfish and Charlie.