How do I emotionally deal with a large inheritance?

First of all, to explain the name and so y’all can mentally place me: I’m a 5K flutherer, been around for a bit over a year. Hi, friends!

So here’s the story: I got home today to find a large check from my grandmother’s estate sitting on my counter. She died a year ago. This was utterly unexpected – a bolt from the blue. I texted my SO, called the estate manager to double-check that it was real, and then cried for half an hour. This is more money than I expected to have all at once for several more years – I’m in my mid-twenties and still in grad school. This is the first time I have inherited anything. I didn’t think that she had put me in her will. Is that even what this means? I feel so…guilty and confused and sad, and I don’t even know that those are the right words to describe what I’m feeling right now. At the very least, I am suddenly super stressed.

Is this normal? It seems like I should be feeling something along the lines of happy, right? Can any of you with experience in this area tell me about what you felt like when this happened to you?

And, is it a bad idea to put this question out here, privacy-wise? I’m sure I could ask Augustlan to take it down if you guys think this is stupid.