He's a grown man, and therefore old enough to know how to treat other people with respect and do so if he wants to.
A text message telling-off from you will make zero difference to him for the obvious reason that he either doesn't have any respect for you in particular, or other people in general. If he did, he would have behaved differently.
You say you want to 'reclaim some dignity' but you don't need to contact him to do this.
You have realised that you did not know this person as well as you thought you did, so you can reclaim any potential loss of dignity by asking yourself carefully if there was anything at all in his previous behaviour that could have given you a clue that he might behave as he has.
If there really wasn't anything, then you can conclude that he puts up a very good facade, and you should feel no loss of dignity in having taken him at his word. All the shame is with him.
If you realise there were in fact some potential red flags that you overlooked in your excitement to get laid, then your dignity is reclaimed by recognising your own fault in the matter and resolving not to repeat it.
Once you've done this exercise, block him, dust off your hands and go buy yourself some flowers.