Ex husband has filed to a conservator for our autistic son

If you were the custodian parent, you likely have priority to be appointed conservator. The court would have no way to know that background. The first question is: does your son need a conservatorship? Some kids on the autism spectrum need only a conservator of the estate, so they're not exploited. Others need full conservatorship. If your son can function at a middle school level, he may or may not need a conservatorship. If he's non-verbal, non-social, he probably needs a conservatorship. In particular, if he's not able to communicate well with doctors, you will need a conservatorship in order to have the right to direct his medical care. You need to immediately file a response to your husband's filing. You can either cross-file a petition for conservatorship, asking that you be appointed conservator. Or you can file a response that states you do not believe your son needs a conservator. Time is of the essence here, and you will really need an attorney for this.