Going to be a mom a 19..

So I recently found out I’m pregnant. I’m 19 (I’ll be 20 when I have the baby) and my boyfriend just recently turned 20, and I’m having some really mixed emotions right now. On one hand, I’m so scared and nervous, but on the other hand I’m thrilled.. I do plan on keeping the baby and my boyfriend is on board, he’s actually pretty excited. We have our own place, we’re in a good place financially and I’m already enrolled in online classes for psychology. We weren’t irresponsible like most teens/young adults, it’s almost like it was meant to happen because I thought for sure that we were good, which I know every time you have sex you’re taking a risk but when you still get pregnant while on birth control and using a condom it seems pretty crazy (condom has a tear in it and I was on medication that I didn’t know interfered with my pills). His parents already know and they were a bit upset but they’re honestly excited, but I need some advice on how to tell my parents. I don’t want to seem like this is a bad thing, because honestly it’s not but I don’t want to just blurt out I’m pregnant. My boyfriend suggested writing them both letters thanking them for all they’ve done for me, etc. then at the end of the letter tell them the big news. Any suggestions help, whether it’s a different idea or how I should word the ending of the letter. Thank you. 😊