If he"s invested 28.3k (5.3k pre, and a post flop raise to 23k), there is no way I can ever imagine he would fold leaving 22k behind. Speech play, or any other stuff, is somewhat irrelevant - we have to assume he"s never folding now.
As for your choice, having found yourself in spot (I don"t like the way you got to this spot btw), surely you can"t contemplate a fold? It plays itself from here - you jam, he calls....
The reason I don"t like the way we got to this spot.... I can understand the re-raise pre given your comment that the MP player has raised a lot of hands.... But, I hate to play a bloated pot out of position with a hand that could very easily be dominated if we get a caller (ok in this situation, the MP folded and the SB called, meaning we are now playing the bloated pot in position).
When we"ve flopped such a huge draw, do we need to semi-bluff?.... given that we have position, is this perhaps a spot to check behind for pot control, and also to disguise our hand to some degree if we hit on the turn? By making the semi bluff, we open it up for the check/raise, and now have to play the draw for most of our stack.
What do we put the SB on prior to us making the bet on the flop? He"s playing out of position, but has called the original MP raise, and has called our re-raise, yet you already noted that he folds under pressure. I think it"s a reasonable assumption that the flop has smacked him fairly hard, and for that reason, I advocate checking behind on the flop.