The general rule is that all property acquired by either spouse during the course of the marriage, regardless of title, is marital property and subject to equitable division. Assuming that the property in question was truly marital (versus separate property), then you have rights to it. In divorce proceedings, you can enforce those rights. As to charging your wife's friends with tresspassing, you have no claim. The fact is that your wife was a legal resident of the premises (and possibly an owner), so was allowed to legally invite guests onto the property.