How do I approach this situation?

So my baby dad wants nothing to do with my son. I already have spoken to his parents and we were under agreement if He refused a DNA test ( per their request) they would take a DNA test. I spoke to her two weeks ago telling her the baby’s name and stuff. She has her email and phone number on instagram. Should I use her number on instagram and send her a text or write her a message on instagram. This is what I would like to say:

Hello Tina, I am reaching out just to let you know I have seen Sergio. He said he doesn’t need to take it Based on the conversation you and I have previously had, if Sergio refused a DNA test a grandparents DNA test would be given. Regardless of if you choose to be in my child’s life or not. I understand as Sergio’s mom you’re always going to be on his side, so if him not wanting to be in his sons life means your family don’t want to be involved that’s fine. I’m not trying to force my son on anyone. USPS dropped the test off to you about two weeks ago. Please let me know when and if I can come get it.