IIRC, the Spatone appears to have a small amount of iron in it, but because it is so easily absorbed by the body, it has the same impact as a much higher dosage tablet.
I'm anaemic at the moment, and feel utterly dreadful. No wonder you're struggling with everything else on top of this! I can barely get upstairs without gasping for breath and going dizzy - you really are doing far too much which won't help. I've been prescribed 3x 100mg ferrous sulphate per day - it would be worth double checking that you don't need to up your dose considerably as yours sounds low.
I've been where you are several years ago - hated my job, stress everywhere I turned, young kids and a terrible relationship. I can only echo what others have said, as I didn't slow down or stand up for myself enough. In the end I just ended up walking out of work one day after losing it and yelling at one of my team. I was signed off sick for six months on antidepressants. I returned feeling a bit better, but within a few weeks it was worse than ever, plus no one took me seriously any more because I'd been off sick with stress. I had colleagues deliberately stitching me up and setting me up to fail (was once accidentally copied in on an email where several of them bitched about me and plotted to get me out, I was devastated).
So in the end I resigned with nothing to go to, as I had just run out of energy to deal with any of it. It was very stressful but I got another (much lower paid) job which I was much happier with. It's worth considering any and all options even if they don't look doable at first glance.
I know so many women with families who struggle to maintain their careers, relationships, deal with elderly parents - it is so hard to do this and keep sane even without health issues on top of it. I hope you find a way through this, OP. Your GP sounds shit, I would start by getting in to see someone else if at all possible.