What is the best way to deal with Existential ocd. I don’t have any physical compulsions but they are mental. I’m having a hard time not mentally checking things not to freak out. I get dpdr as my panic attacks surge.

Just have faith trust in God and give your ocd to God put it in God's hands and trust Him. Seek therapy and anything that is at your reach to get help in a healthy way and trust in your Heavenly Father who will never abandon you. God bless you. HE LOVES YOU!