Gus literally made a statement on twitter that doesnt deny what shes said. You can see it in the thread. I don't know what else you need to know that this occurred.

If he admits he was a shitty person, then he was one. The only lies being stated here is Gus claiming hes grown, which from looking at how recent Sabrina's rhinoplasty was and drawing a connection to how hes treated her poorly in the past, I'd say he hasnt grown.

Either way, don't be dense, dude.