Would I be the drama for quitting my job

Hi guys, I'm in a massive dilemma here and don't know what to do. For the sake of the post, you can call me Jen (30F).

I started working at my current company a little under 3 years ago. The agreement made was that they'd train me up to specialise in medical writing so I could take on more client work over time. While I underwent training, I'd also help out with in house marketing, which was what I'd previously specialized in but had applied to this company expressly because I wanted to try to specialise in the health/medical writing. It very quickly became apparent that I was mostly needed for the in-house marketing stuff and I essentially became a one woman marketing team with little to no support or guidance from the MD of the company. Essentially I was told to 'take ownership' of the company's entire marketing and PR strategy. This continued for about a year and a half before I had a huge dip in my mental health. I wasn't feeling supported at work in terms of my job role and then I had a lot of personal issues to boot (my marriage broke down and I lost my grandad who I was very close to. Despite being made aware of these issues,the MD continued to push me harder to do more and get more results at work. At one point, in a meeting with other people about a month after my grandfather died, he asked me why I looked "so pissed off". I, regrettably, immediately started crying - I have ADHD and emotional regulation is not a strong point for me, especially when I'm being spoken too aggressively. I tried to apologise and explain that I wasn't pissed off, just not having a good day given everything I had going on and hadn't realised it but as obvious from looking at me, but he cut me off, saying, "I don't want to talk about this with you now" and ended the meeting. This was one of several incidents where he was rude or insensitive to me or belittled me. He would frequently tell me my work was s*** despite my efforts doubling our social media following and digital footprint and he would often give me contrasting info wh n meeting alin so that he could then contradict or trip me up in meetings with other senior team members. When I eventually raised this with my direct manager, I was told I wasn't the first person to complain about him and that I'd be taken off the marketing work as soon as possible if it was making me unhappy. I was, eventually, given the training I'd been promised originally so I could focus on client work, although this took 2 years from me being employed. While I do now work significantly less on the marketing stuff, whenever I do, I still have to deal with the MD, and everytime I do I feel sick to my stomach. My confidence is in tatters and I physically dread going into work. I may have an opportunity coming up to leave to work with a manager I've worked with previously and worked well with, but as my current company only recently paid for me to go on this training course I feel guilty for thinking about leaving. But then I think about staying and continuing to work with someone who makes me feel so terrible, even if it's less regularly now, and I'm sure leaving is the right option. But would I be the asshole for leaving now?