Hello and welcome.
Potential resources...
Reading:
Divorce Poison - Warshak
Don't Alienate The Kids - Eddy
Co-Parenting with a Toxic Ex - Baker and Fine
ISNAF:
https://isnaf.info/ - much longer list of resources available on this site
Online community:
https://parentalalienationanonymous.com/ - advocates a 12-step program including acceptance of a higher power - may or may not resonate with you, but you may find it useful to connect with a diverse community with shared experience. I attended a few sessions and gained some perspective: My 16yo daughter still spends time at my house, albeit with maximum opposition. Many people at PAA meetings are completely iced out, some for decades. Everything is relative. The lesson at PAA is: It takes two to fight. So don't fight. It's very hard to put this into practice if you have contact or recent contact with your child.
Consider reaching out to local family services and ask for referrals for Family Systems Therapy (different than reunification therapy) - this could be a good vector to identify resources in your area who are aware of PA dynamics, and who may be able to help you identify options, even if you don't engage for Family Systems Therapy...
There are many providers / professionals / youtubers / facebook groups / instagram experts cultivating what I think of as the "Parental Alienation Industrial Complex" - My $0.02: litigation is rarely a solution to psychological problems / family dynamics. Legal professionals are gaining awareness of PA, but... it's difficult to manage, at best. I haven't heard of a single case of successful reunification therapy - many stories are just the opposite.
At or near the top of experts and advisors is Amy Baker:
https://www.amyjlbaker.com/It's good that you're seeking resources and support. Take your time, do your diligence, remain skeptical of magic bullets, and above all: As you navigate this harsh landscape, take care of yourself.
Take care, and please let us know how you're doing.