One thing to watch out for is generalized depression. It can make it seem that all projects are not worth investing in. It may seem to be related to this project but it may be a wider issue for the individual.
It's insanely stressful and discouraging to be harassed, threatened, pseudo-stalked and have your work stolen for profit. Often the healthiest thing to do is to walk away from toxic situations and invest your time, attention and pursuits elsewhere.
That said, circumstances like these can certainly cause lasting depression. I just don't perceive the OP's behavior stemming from depression, it seems like a perfectly logical and healthy reaction in response to a shitty situation.
I mean, perhaps they have depression, but this is pretty awful. It’d make me want to quit.
I personally have experienced a lot of bad stuff too. It is sort of par for the course if you make popular projects. I'm lucky that I'm not that affected by these side effects of high profile projects.
But I've known of two different individuals I've collaborated with (I've worked with a lot of people over the last 30 years) who have suffered from real periodic depression and it exhibits itself as emphasizing everything bad and minimizing anything good and basically saying nothing is worth it. In the moment for these individuals they truly believe this, but it is actually a real depressive episode that is colouring their judgement. I think the depressive episodes have triggers, but most of what gets described as the cause and the situational problem is just a symptom of the depressive episode. At least this person is acting, the more worrisome type of response I've seen is a lack of action/withdrawal as that doesn't really fix anything and then it isn't clear how long the episode will last.