I'm going to message my ex but I don't know what to say?

[white lilly]

You are in his PAST! Get it?
Move on and forget about him.
He has moved on and forgotten about you. He has a FIANCE that he loves and she loves him.
How dare you try and come in between that!

He was wrong for contacting you at all during the relationship, but if he has now cut you out of his life then great, and you should get the message and stay out!

If you try to contact him and pursue him then if he loves his FIANCE he will tell you, his pathetic ex who wasn't good enough in the first place to get lost. And rightly so!

You really do sound pathetic.
Find someone who wants you instead of trying to take someone else's FIANCE.