Am I being unreasonable?

[Bailey93]

I don't know if this is the right place to post this, or what I even want from this post.
But my partners dad drinks, a lot. And comes to stay with us as we live a 4 hour drive away. I can't help but find it extremely stressful when he is here. He leaves his stuff everywhere. I have to put old sheets on 'just in case' and he's often sick in the mornings leaving the mess behind for me to clean up. Am I being unreasonable for getting annoyed by this? I really do try but I can't help but resent him every time he comes and I feel like I'm not any fun to be around. The whole time he's here I am annoyed and on edge and often find reasons to get away, or come up to the bedroom. It's normally about a week that he stays aswell. I guess I just want to know if there's anyone that's in the same boat!! Or what I can do to get through these times!

Be honest, in the nicest way you possibly can. You should speak to the dad directly, perhaps when he is sober, in the morning? Just let him know how you feel. It is better to be open and honest rather than bottle it up and let it come out in annoyed and negative atmosphere or worse, in an explosion of anger.
If your partner or FIL doesn't see your side to things - then leave the mess. If you believe it isn't your job to clean up after utter carelessness then don't, perhaps that will get the message across in the end.