If you are sure you don't want to go back to them, your best bet is to write them off and move on. It might seem unfair and/or their answer may not be what you would have expected but there is nothing you can do to change their reactions.

They may be surprised, they may have reacted poorly (e.g. female T), they may not want to 'chase' clients etc. Who knows. These are mere assumptions.

Leaving them was painful enough from what you write. Don't compound it by further analysing, second guessing or torturing yourself.

IF you did want to continue seeing them (nothing wrong with that, either), then tell them. Otherwise, close the chapter and move on with your life. The alternative will only make you feel worse.