There's nothing pathetic about being scared. Emotions tend to be out of our control, especially the likes of fear. It's part of that survival instinct.
It could be the nightmare, it could be something from before you fell asleep or the day before, or maybe there's something you know that's coming up that's scaring you without you being fully conscious of it.
It sucks that your sleep was disrupted so horribly. If I had to guess, the disorientation from waking suddenly and the lack of sleep probably aren't helping your current state. Sleep deprivation can negatively affect mood, I'm pretty sure.
Maybe if you have a comfort song, beverage, food, movie, or anything at all that puts you at ease. ... you could try distracting yourself with it to calm yourself and then see if you can try and get some more shut-eye if it isn't too late for that. Of course, that is only a suggestion. Anyway, I hope you manage to find some rest, and some peace from whatever is scaring you.