It’s incredibly difficult to get good services for children on the autism spectrum in most areas here in the United States. It sounds like you’ve gone through a lot of local resources already. I don’t know if you’ve contacted any of the national ASD organizations, but they may have additional guidance and resources to suggest. The Autistic Self Advocacy Network may be one place to try.
With regards to the sexual abuse, I would suggest filing a Child Protective Services report. If the school is attempting to make light of the incidents and not follow through, having the State address the issue is a way to ensure at least some follow-up and accountability. It would be an appropriate next step to help protect your child. They may also have resources they can bring to bear to help with the treatment of your child, including resources specific to sexual abuse and behavioral interventions.
If you have private insurance, some providers now have “case managers” who are involved in helping connect families or patients to resources with the goal of enhancing outcomes. It may be worthwhile to try to contact your insurance carrier if you haven’t done so already to see if they have such a service. If you have a state insurance like Medicaid, contacting the local community mental health and requesting additional resources is another option, but one that you’ve likely looked into already.
It sounds like you’re doing the best you can. The system is so incredibly broken and not easy to navigate. If you haven’t connected with the National Alliance for Mental Illness (NAMI) you may also want to reach out to them and your local chapter to get support for yourself and your family. Sometimes they have resources they can share, but mostly its about being connected to other people to support you through this struggle. Many NAMI families have faced similar situations and may have tips to share as well.
I hope others reply here with additional advice. Thank you for being such an advocate for your child, and hopefully the help will come.