After I told him I was pregnant, suddenly everything I did wasn’t good enough

I work as a fundraiser for a charity. I write fundraising bids, really just writing letters to trusts and foundations to ask for money. I have worked for my employer for 3 years. I started off at 10 hours a week after returning to work after having 2 children and working my way up to full time when they were both at school/nursery during the week. As of January 2016 I was working full-time from home, coming in to the office when needed for meetings etc., usually once a fortnight.
I found out I was pregnant in February 2016. As I worked from home, no one knew about this and as the months went by I only went in to the office when my boss wasn’t in, or I’d wear big jumpers. I knew from the start he’d be awkward about it (he has very old fashioned and out-dated ways), so I had no desire to tell him before I had to. There are only a few other employees, and I had not told any of them.
I told my boss I was pregnant at the end of June 2016, which was just over the 15 weeks notice you are required to give your employer. He was clearly shocked, he didn’t say much. The next week I came in to the office to pick up some supplies and he called me up for an unplanned meeting. He told me that he couldn’t afford to keep me anymore and that from the end of the month (3 weeks away) he was cutting my hours to part time. I didn’t say much at the time, I knew he couldn’t do this so I got straight on to an employment specialist solicitor.
He advised he couldn’t do this and he wrote to my boss on my behalf. At this time my boss started picking on EVERYTHING I did. I couldn’t do anything right. He made me re-write all my bid letters. He signed some off as fine and then weeks later would say they are terrible, even though he approved them himself. Everything was wrong, he started asking me to keep records of things I had never had to before. He was being so unreasonable that I once asked him to help me, give me an example of what he wanted me to do, but he downright refused. I have obviously kept all the correspondence as it was all via email. By August he had stopped me sending out any funding bids, effectively stopping the charity from getting any income, as I was the only fundraiser. He replied to my solicitor and told him I was under performing. He started using different tactics to get rid of me. It started off that he couldn’t afford me, then it was that I was under performing. Yet he had never given me any written targets. Until I told him I was pregnant I was bringing in good money and he was praising my efforts every time a cheque came in the post! His attitude changed drastically from the day I told him.
At the time I was enjoying my job, I had planned to take just 2 weeks maternity leave and then return to work, as I work from home this was easy to do. He started saying that once I returned I would only have part time hours. Back to my solicitor who informed him that I had every right to return on my current full time contract. This was not good news for him, he then tried another underhand tactic to get rid of me. He told me that when I return I would be required to sign a new contract, this contract states that I will return on my full time contract but I MUST be office based, working office hours. Now he knows full well that I can’t do that. I have 3 children. My school runs are during work hours. I work my 35 hours a week during the day, evenings and weekends. I get all my work done, I have no need to be in the office and I always come in when expected to. He knows I can’t be based in the office and this is how he will get rid of me.
After many stressful weeks I decided it was safest to return to work after I had taken the 39 weeks of maternity leave. I need the money, I wanted to return sooner, but as soon as I do he will dismiss me. So I will return in July 2017 as we cannot afford to have no income, I have to go back to work.
He will ask me to sign my new contract and I will refuse. He will sack me. I can then take him to a tribunal for unfair dismissal. My solicitor has been fantastic and I wouldn’t know where I stood without him.
I am determined to fight him to the end. I cannot let him win. He runs a charity, one he set up himself but he hasn’t got a charitable bone in his body. I have had great support from other staff who have been shocked by his behaviour. It seems over the past 9 months he has bullied trustees in to leaving and has been very nasty. I had never seen this side of him before.
I refuse to let him win.