AITAH For thinking my GF is Lying and refusing to believe her?

Heya all, this might be a lengthy post as I want to make sure include everything for my reason and in the cases where I felt like I was an asshole too to get a general opinion from people as it seems to be the only opinion im getting is from biased people.

So I (32M) have been with my partner (31F) for 6 months, but there seems to be an awful lot of lying.

We started seeing each other and it was just sleeping together ect, just before we became official I got a message from a FB account showing me screenshots between her and her male bestfriend (from his whatsapp it seems to be) Showing that they had been sleeping together whilst we was, She had previously told me they hadnt been and nothing was there, when I confronted her, she lied to my face, and then came clean a day later. This was the First Lie. I forgave her as we never had the exclusive talk and just made her aware I was more annoyed she lied than that she had been sleeping with.

A month or so later a bigger issue started. She had an ex situation-ship that she was obsessed with. This guy didnt want to be in a relationship with her whilst she did and pretty much fell for him, throughout the course of our relationship she blocked him and unblocked him on repeat and basically couldnt stay way citing that she felt she had trauma bonded with him due to how he treated her. Dispite knowing she was conflicted I supported her and stayed.

The second lie she made has presented itself. She Added him on snapchat and changed his nickname to something else to try and hide him from me, when showing me a convo on her snap I recognize his bitemoji and I confronted her about it, she initally lied to me telling me it was her brother and then eventually after she realized there was no way out of it, She came clean admitting she did it and said she just didnt want to hurt my feelings or cause an argument over something that was innocent and totally platonic.

Okay, Sooo fast forward to December. I recieve a friend request on snap from her ex situation-ship with screenshots of her messaging him on tiktok and asking him to block me if he wants to readd her on snap cause whenever he adds her, it shows him up as a friend suggestion to me (I told her about a month before that he has appeared as a friend suggestion)

The convo continued her telling him that she feels a pull towards him even if i am a good guy she still feels a pull there and shes not sure why. And she event sent messages saying that she will consider going to see him on a train ect.

Intially I kept this incident to myself cause I wanted to see if shell come clean and tell me, In january I had a girl message me on tiktok claiming that shes also been sleeping with him and he saw my partner and him talking on telegram. I showed her the messages and pleaded that she hadnt, and that she doesn't even have telegram

After this, I did something and went through her tablet knowing it was synced to her phone. It had telegram installed and even more had screenshots on it from the convo she had with her ex situationship in december but from her point of view. I do think IATAH here for going through her tablet I broke her privacy and I shouldn't have done it, even though I had found something.

When I confronted her and told her I also got the screenshots sent to me in December, she lied to my face and she consistently tells me its a "fake" account, someone pretending to be her to try and split us up. I do not believe that its a fake account and I believe she was talking to him on telegram after finding telegram on her tablet.

Since then she had changed her passwords on all her devices.

She has since diverted the arguement into other arguments, telling me I always use a tone of voice and talk over her when shes trying to tell me a situation or how she feels and thats why she always lies and dont tell me anything.

I do feel like AITAH for raising my voice and talking over her, but I do only do this when I try to give her my reasoning or point and she instantly dismisses it and just flats out tells me im wrong for thinking that way

AITAH for not believing her on The December and January incidences due to her previous lies?

Update: After all of this, her Guy best friend all the way from the first lie at the top of the post messaged her on a fake account admitting to being the fake account and to trying to break us up, and then messaged me the same thing, except when he did she was in the bedroom on her own with the lights on and the door shut. I also dont believe this and feel like its her messaging herself to try and gain evidence to make me look like an AH and like im just paranoid and insecure.

The reason I believe this is because only one of them were active at once. and her FB account was inactive for the same amount of time His fake FB account was messaging me. Also after that night, he never went on the FB again and never heard of again.

AITAH for not believing her on any of this? Looking for some true opinion from people that dont know us.