Are ghosts real? Or was I hallucinating?

I woke up around 3:30am last night cuz I had to use the bathroom and be aware. I was extremely tired. We have a pantry that's a clear glass door. It was open, so I closed it. I went to the bathroom & came out & it was open again. So I closed it, again. I was on my way back to bed when it flung open and I swear I saw something creepy & black run out of it & it made a groaning sound. When I went to go close it again, I got so many chills, I had goosebumps on my goosebumps! And when I went back to sleep I kept waking up every 15 minutes from sweating. (and it's VERY cold in my house...weird). Do you think I really saw that? Are ghosts real?!