Welcome to the forums.
I'm so sorry to hear what your family is going through right now. I'm glad you have reached out here tonight.
It's so hard to feel like you want to say more but are afraid of saying the wrong thing. It sounds like you are doing a wonderful job of letting her know she is loved, which is so important. Providing a safe, loving, non-judgmental space for her to talk can sometimes be more important than having the exact right words to say. I think it's important that she feels safe to share and knows that you are interested to know what's going on for her and won't judge her, whatever that might be.
The Suicide Call Back Service have put together some information that you might find helpful:
Supporting someone after a suicide attempt
I'm sure others on the forums will have thoughts and suggestions too.
Welcome once again. I hope you find the forums a helpful space to share and connect.