It's not stupid...I am imagining myself in your shoes and how I would feel...it's the shock and loss and confusion, too...I would feel like, but how could I not know she was gone? And you don't elaborate, but the circumstances could have you completely torn up as well. So very sorry for your loss and grieve as you need to.
And stop thinking she was a better person than you, which I don't believe can be determined, based on what? There are no tradeoffs here, and it's not like even if you had the chance, you COULD you have given your life for hers...it's sad, but it's true. Please be kind to yourself and take the time to remember the good times with her and the good things about her, and also your loss.