Is this cheating, I found out my now ex girlfriend has been seeing her ex, I found out online cute photos of them together?

Libra9292

So as the title says,

4 years completely destroyed, my now ex girlfriend claims she's done nothing wrong and because she breaks up with me every week it doesn't count as cheating, she says she never slept with him but she did see him because apparently he was sad, because his fucking dog died,

And recently she's been comparing me to her ex a lot during arguments, arguments that she's caused, I don't have the energy to argue with her at all, because it ends up me being blammed for everything, so I try my best to not doing anything wrong living on egg shells

For the last 2 years she's made my life hell, destroyed my mental health made me out to be crazy, constantly acussing me of being a cheat or unfaithful, abusing me for even speaking to female work colleagues or saying thank you to female waitress,

I've blocked her now on all forms of contact,

It just sickness me even tho she's been caught having cute hang outs with her ex, she tried to burn me even more telling me I'm the worst person ever, telling me she doesn't even want to be with me, we was literally having sex together 5 days ago looking at holidays

Updates
8 mo
When I posted this message I didn't really explain how I found out correctly as I'm still stressed, this all came out yesterday, well we had a day booked together at ranch for horse riding an archery, but typical her, she caused another argument, which led to her breaking up with me again, an her telling me how her ex was great and I'm so bad, so I called her bluff I Facebooked him turns out 5/6 weeks ago, she was hanging around with him, videos together love heart filters
Updates
8 mo
It's been a strange day today, knowing that it's completely over, like that feeling of emptiness,
Does she have regret?
Is she sorry?
Does she realised her self I'm gone for good?

Like I don't get why you would spend time with an ex for what ever reasons, like I would tolerate it
or allow it.
Is this cheating, I found out my now ex girlfriend has been seeing her ex, I found out online cute photos of them together?
8 Opinion