I'm so sorry for your loss. That is unimaginable. Her comment was insensitive and offensive and you're clearly hurt and annoyed by it.
It is playing on your mind so you should mention it to her to clear the air a bit, otherwise it will stand between you in your relationship.
It will be just another one of those things that you think about the next time there is any kind of issue between you two, and make you less close when it doesn't necessarily have to if you discuss it now.
I think the comment she made was insensitive and unusual and obviously has negative implications to her own daughters as well. (They didn't hear it, of course, but the implications of her comment that perhaps she'd rather have a good relationship than both living children, or that there's even a comparison to made there, are still pretty bad).
That aside, I think she probably felt shut down and that once you brought your pain into it meant that now she didn't get the right to talk about her pain any more. You made the conversation about you and your loss, which pretty much makes it impossible to complain about anything ever, because your pain is obviously always greater than whatever more minor thing she's upset about. It may well have felt like you were shutting her down, even though that wasn't the intent.
This is naturally upsetting and if you want the people around you not to shut down and not talk to you about what's actually going on in their life and how they feel, and stay close or get closer to you, then it's better not to say things they unintentionally shut them down when they're opening up to you.
Unintentionally upsetting someone is forgivable in my opinion and it seems like you've both done it, and under the influence of a lot of wine so it is understandable that both would upset the other without meaning it.
Clearing the air and both apologising will probably go a long way to make this something you can both just try to forget about and not have this be an ongoing hurt you both hold onto in your relationship.