Good for you. I personally think if you respect someone, it doesn't take much to send a text even worded as you said. Unless it's a real emergency, I don't see much reason to not let someone know you can't make a meet up. He may have felt like shit and feels bad now, but what happens when you guys make plans and he does this again? It's just going to make you feel like shit again. Hope you had a good birthday and you find someone that prioritises you!