There must be a reason she is wanting this.........
First of all, your "ex" has made a claim which is an actionable tort.
It is called a "per se" tort, because the acusation itself does such harm to a parson's reputation that the only question is "how much damages?"
There are, however, some "missing pieces". Have you EVER used cocaine, for example?
I am not sure where you are posting from, but in the United States, such a claim must be presented before a family court judge, who would order a test or disallow the claim.
Laws vary everywhere, but where I live, if its her allegation then the burdon to prove her claim falls on her. Do you have an open court case? She made these allegations to the family court? Sometimes they court will require a blood test for drugs but if its based on one person claiming drug use of another often the costs will be split. Do you have a family court probation officer? What state are you in?
I can help u look what city r u In? No hospitals or a drug screenning place. I know where I'm from they have a special building for drug tests only.. But get back to me and I'll try to help u