According to the Internet, a step-dad is a real man who steps up and is willing to take care of someone else's children, and you did just that. You are more of a dad than my real dad. You have taught me the rights and wrongs, you have loved me when my father wouldn't, and I am thankful for that.
I know we haven't always gotten along, but I haven't been the easiest to raise. Now, being an adult, I am thankful for all the times you've yelled at me and grounded me.
Thank you for being the man I can call when I get a flat tire or something happens to my car. Without you, I would be stranded in the middle of nowhere with a flat tire or a smoking car. Thank you for being the man who can fix my car and tell me that it is in fact smoking and going to blow up.
When I was little, I never understood your parenting. I thought you were just being mean, but now… now I know. You weren't trying to be the evil stepfather, you weren't trying to make me hate you... All you were trying to do was make me a better person… and that I am thankful for.
I am not only thankful but I am grateful that you married my mom and came into my life because, well, we needed a father figure like you.
Sincerely, Your Daughter.