Don't Let Guests In If You're Busy

So it seems like I never learn my lesson.  I also get really stressed out when people stay at my home.  I work from home and people don't respect that I'm busy, so when they come over, it's INCREDIBLY disruptive and stresses me out beyond belief.  Listen to my latest fuck-up where I let an old friend and his mom stay with me and now I'm paying the price.