Rising to the Occassion- Sometimes It is Harder Than it Seems

My mother in law is going to be joining us here for three weeks in March. I am happy that my husband will see his mom and that my children will get to see their grandmother, but sometimes getting excited about her visit is harder than it should be.
My husband is under so muh stress at work that he just doesn't need anymore. Some days he works from 6 am until 9 pm or later, and when he finally comes home, he is just dragging. I mean, the minute he puts his self down on the sofa, he's asleep. My mother in law, like the rest of the women in his life, enjoys his attention - and LOTS of it. Her visits aren't enjoyment for him, but usually WORK, which really increases his stress levels and makes both him ( and her!) impossible to live with. We almost always fight while she is here, and we rarely do any other time. It's very frustrating.
This year, I don't want to add to his cares and concerns. I'd really like to have a nice visit with his mother, but I'm worried. I say this every time she comes to visit and yet, on every visit, rising to the occassion is harder than it seems. She has a vast array of weapons in her arsenal, each one uniquely designed for getting under my skin.
I guess whne I am truly honest with myself, what it all comes down to is the fact that I hate to share my husband. Our time together is so limited and to share what time we do have with someone who is so annoyingly needy really gets me. This time I want to stop being selfish and really try to make her visit enjoyable for him, but I'm not sure how to do that.
I love my husband and I want to help ease his burdens, not make them worse. Does anyone have any suggestions for me? Whatever tips that you use to help make your MIL's visits enjoyable - I'm all ears! Thanks so much!