I'm sorry that you are having such difficult experiences when it comes to your mental health.
My workplace are incredibly supportive. I have schizoaffective disorder and have had to have about a month off each year for my mental health, generally at the same time. I once had three months due to being detained in hospital for two of them and recovering in the community for a month after discharge. They left me back on phased return, and they even dropped me off some bits to the MH ward, which is on the same grounds as the medical hospital I work in. Sometimes we laugh about things, but that's not a bad thing in my case, because often I can find the funny side too - so they're laughing with me, and not at me. I know it's hard when you've been treated badly in the past, but there are good employers out there and I am sure that you will find one when you feel ready to work again.
With benefits, I've never had any problems either. I don't claim ESA, but I have claimed other things purely for mental health reasons and haven't had an issue. I've sent of evidence from the mental health team, my employer, my Mum and my GP and it's been OK. I didn't have a face-to-face assessment with PIP as they went on the strength of my medical evidence, and that's when I'd been out of hospital for a good couple of years and was not at my worst. I don't really know your story, but have you been to the CAB about your struggle with benefits? I know in out area a local charity has someone who deals with claimants with mental health issues and nothing else. Might be worth looking into something like that, if there's something in your part of the country.
I have some great friends. I don't lie to them. I'm open on Facebook about my struggles and say that I'm feeling too anxious/am having a bad day if I don't feel up to going somewhere, and have had no judgement. I'm sorry you've been on the receiving end of such remarks about your mental health. It's really important to have people around you that understand and it's terrible that you haven't got that. I'm wondering if finding real-life friends with difficulties similar to your might be helpful? Again, there are charities in a lot of places that facilitate drops ins and things that might be able to help with that.
Have you sought any support from the voluntary sector? Mental health centres? Charities that provide support? There are things around that can help you without needing to be referred to.