What you gave her was judgement and pressure. Telling her to take some time and make sure she's certain of her decision is fine, if you'd left it at that it would've been fine but you put on your preachy hat instead and decided to make her feel even worse in the hopes you could guilt her into doing what you want.

"You're killing your offspring" isn't advice, it's an accusation.

She knows that adoption and keeping the kid are options. You didn't enlighten her with any information she didn't already have, you weren't making sure she was aware of her options, you were making it clear what options you wanted her to choose from while vilifying her for the option she's already chosen.