If you instinctively know that what you want to say is the right thing to say, then you are more than likely to be correct in your thinking.
But then the mind takes over, we over think, we lose our courage and we end up not saying it. Then we fester about that and beat ourselves up for not being brave enough to say what we really feel.
Then when it gets to us, we usually then end up saying what we could have done in the first place, but it comes out with all the anger and frustration that we’ve built up with ourselves.
Just say it and say it straight-away, don’t leave it, it never gets better with time.