Good luck dealing with them. If they are really your friends they will understand and move on. It can be hard to do but you need to step up and get them out. The stress your under is not worth the money they are giving you.

I own my own house and rent out some rooms to make ends meet and I have kicked out my fair share of friends and family.
I have a no smell policy. I have a crazy gag reflex and the slightest smell will get me going. Some days my rats even get me gagging. No smoking, no drinking, no stink one strike your gone. I had a friend move in and before her stuff was even in my house I kicked her out. Her stuff smelled like cat urine and cigarettes..