How do I make up for flaking out on a guy

I flaked out twice on a guy I was texting. We went to high school together, but only started texting when I saw him on an online dating app. I was really starting to like him and now I feel stupid and shitty for being so.... STUPID AND SHITTY!! Any ideas how to make it up to him? P.S. He's not responding to my texts anymore (and we texted all day everyday for 2 weeks) but I don't want to seem needy and keep texting him. I really want to though, but mostly I just want him to know how I feel: stupid and shitty and sorry and that I was really starting to like him.