Hi Claire,
I would keep all the stuff that means/meant something to you. As a girl, I think we need to understand alot more thoughts and feelings around why things happen. I think when your daughter is older, perhaps in her teens, she'd like to see more sentimental things of her dad. I would keep the cards and the wedding ring, even just for your daughters sake in 16 years time. Thats just my opinion anyway as I have never been in a situation like this. Only you can decide whats best. Good Luck!