Am I being selfish?

Hi all! My sons grandma did a grandparents dna test and it came back positive she IS my sons grandmother. However I have reservations about her. She’s been playing both sides of the fence, and when I reached out to her about the dna test she ASKED ME TO BUY. She said thank you for letting me know and never responded to me never asked his name nothing. She claims she hasn’t spoken to Julian’s father about him and he hasn’t spoken to her but when I talked to her she said she’d talk to him. My sons dad wants nothing to do with us which is fine, he wants to be able to have sex with me but not take care of his child and I said no and cut it off. So he blocked me from Facebook, we have no method of communication. I don’t know these people. I am not comfortable with her being in Julian’s life I feel that is a decision for my son to make. She said she doesn’t want to get emotionally invested prematurely before dna comes back and i completely understand, but she was avoiding me for the longest about the dna test she even sent the first one back! But claims she didn’t. She had a lot of inconsistencies in her stories. Yet her and her hubby remain adamant they want to be in his life. Am I to keep themAway from Julian? I haven’t told her the results YET but how should I tell her?