I think you need to kiss your mother in law and say, "I love you for worrying about us....do you think she felt pressured to call me? I don't want either one of us to pressure her....help me be careful of that ok?" And try to get MIL to back off a bit. Who likes to be pressured?
But the most important thing you can do tonight is be LIGHT AND RELAXED. If she even tries to bring up R talk, stop her and say, let's do that another time...OK, let's have fun tonight. Unless you really have something you need to get off your chest, let's just play tonight.....
