How to cope with unpleasant visitors???

Did you ever have to cope with a house guest who is driving you through the roof? Every year we have the questionable honour to receive my sister in law who is a seventy year old spinster. We - a German woman, her Italian husband and 8 year old son, are living in Goa, India, a place famous for its lucious nature. Goa is one of the main holiday spots in India and our Aunt comes here during the winter time to aquire a nice sun tan and take a break from the harsh temperatures in northern Italy. Unfortunately she considers herself a real lady and behaves accordingly. She arrives with a couple of gifts for our son, some Parmiggiano and prosciutto, stows away her clothes and takes possession of the guest room. With this she has done her contribution. The rest of the time in our house she dedicates to playing with our son, whom she adores. Our son loves his auntie very much and - as she is the only one of our family regularly visiting here - I do not want to refuse her visits. When playing with our son she does not intend to follow any of the few rules we try to establish regarding our darling's education. Instead she brings out her inner child and lets it run wild together with our son which leads to disasters after water battles in the bath room, lip stick deliberately smeared over bed sheets and other nice surprises which I, the housewife, have the pleasure of cleaning up. For the rest she depends on us for entertainment. Whatever we do is fine for her, she is coming along. Unfortunately, I detest this lack of initiative. After some days I cannot help feeling abused by this lady who does not lift a finger to make herself comfortable. She depends on us to make her coffee, to get her fed and to drive her around. This drives me wild as I feel used as a servant. So far I have failed to find a strategy which would help me cope with this guest. Meditation and breathing exercises support me a little bit, but not enough. I envy happy natures who are able to shrug nuisances off and laugh about it. Maybe in some years I will have reached a level of spiritual development which enables me to cope with this lady. So far I take another deep breath when I feel like screaming and wait until the ordeal has passed one more time. And I hope that my patience and tolerance is growing with my years. Let's not get stuck in resentments.