If you are seeing someone, don’t go around sending this kind of text to other people. It’s tacky. It’s unfair. It’s disrespect. It’s time to grow up and spot messing around.
Sometimes your ex hates you so much they wouldn’t get back with you even if you were the last two people on this planet. Do you really want to text them and risking finding out this is what they think of you? You are better off not knowing.