Is it wrong that I'm going to tell my boyfriend that I got an abortion when I was 17?
You did! I didn't  know that. Why are you going to tell him?
We are dating and I want to be honest with him about my past.
It is important to be open and honest in your relationships. While it might feel scary to tell your boyfriend about something like that, it is a good idea to get it out in the open so you can discuss it.
I don't think he will care, so it's pointless to tell him.
It's a part of your past that he would probably like to know. You should tell him about it and be open with him.