I do not want to break bread with a . Can you help with suggestions?

My daughter's husband's sister is gay. My daughter invited my wife and I for Xmas dinner and the gay woman will be there. I told my daughter that I will not accept the invitation. What people do is their own business, but I don't want my wife contaminated by tom boys since she is borderline tom boy herself. For ten years I have been encouraging her to be more feminine, put on a dress and to have poise and demureness. Now she will see that it is ok for a woman to go around acting like a man. All my life I have sought out a real woman--dumping those who were too "butch." I feel that I have a right to protect the sanctity of marriage and not condone behavior over our meal. How can I feel better about this? I do not want to be anti-gay. I just don't want to expose my wife to "Ms. manly" underscoring all that I've tried to do to be satisfied and happy and express my desire for a feminine company. Any suggestions?'Thanks