Hallucination or real?

I was in the bathroom brushing my teeth when I saw an absolutely massive spider. I immediately backed out of the bathroom to get the bug spray, and it didn't take long for me to get it, but when I got back I couldn't find the spider. The absolutely massive spider. A spider that big can't hide easily. It's body wasn't huge, but it's legs made it bigger than a baseball. Small (baby) plate sized. I've never seen a spider that big in person, but now that I can't find it I wonder if it was a hallucination. I've seen spiders that were't there before. Admittedly never that big, never whitish, and I was usually half asleep, but I have seen spiders that weren't actually there before. Do you think it was real or just in my head? Regardless, I'm glad that bathroom is a death field for insects. It's filled with bug poison. If the spider's real, it's going to die. :\