send your wife there for a few months and become a summer bachelor (citing work commitments), if that does not work and she is still insisting on them coming, put a time line on it (2 weeks say), offer to pay their airfares and of course book the flights and what I did was calmly explain to my husband that if they stayed for any longer I would not be able to control what I said to his mother and it could cause a family rift so it was best all round for them to come for short bursts.