Complete and total invasion

I suspected my gf was stealing from me and when I confronted her, she denied vehemently. Only two people had access so it had to be, so I installed cameras in my home. I tried to give benefit of doubt and didnt think I needed to watch all the footage so I set notifications for certain things and watched them. The theft continued, then fights for nothing. I started noticing times off on footage, and glitches only when she was alone. Recently came across a video of a guy with my phone accidentally or maybe not recording himself in my hone while I’m in another room talking about distracting me. I realize she gave him my phone he got all my info, Apple id password, gmail and password, camera app password, and he’s been editing and deleting photos and using my cameras to aid in their cheating literally under my nose. Since I found out he keeps backing up superimposed overlaid images of he and my ex in every disgusting detail but I cannot get anyone to believe it because the photos are overlaid and difficult to make out. I have two kids and I refuse to allow a person who could sneak a stranger into her home with her kids there to take custody do I desperately need to figure out how to take back control of my accounts.