Miserable, Wretched, Unhappy, Sad
な adjective
If you face a lot of disasters in your life you're going to be really miserable. It's a shame, but it's hard to be anything but sad when your life is full of disastrous stuff.
みじめ
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You haven't learned this reading yet so here's a mnemonic to help you: You'll be really miserable if you find out you're going to have a really 短い (みじ) life.
そんなことを言われて、人がどれだけ惨めな気持ちになるのか分かる？
You say something like that, but do you understand how miserable people feel?