Serious issues with landlord-do we file a lawsuit or go to a regelrechter?

Hi all,

The story is long so I will do my best to keep it as short as possible. My boyfriend and I moved in a new apartment in May last year. After about 10 days our whole kitchen was flooded due to rain. It took multiple emails and phone calls for the landlord to respond and finally "fix" part of the problem. After the flood we sent at least 10 emails detailing the issues that need to be fixed(wall moldings falling apart, laminate flooring rising due to the flood, mold growth on one wall that is falling apart, appliances not working..) he never responded to any of them. We tried asking nicely, even offered to do it ourselves but no answer. Then, in October we hired a lawyer. She sent him two different letters in a span of two months, called him, sent emails he ignored her as well. We also sent emails but nothing. We then paid 40% of the rent for December and January(as per our lawyer advice) and told him in an email we would give him the money back as soon as the issues are fixed. He then started threatening with a collection agency, sent an email threatening with changing locks and moving costs and even stated some lies, for example that he warned us multiple times in person that a third person is not allowed to live in the apartment with us. There were a few back and forth emails where he was just an asshole and we decided to not pay rent for February(it's important to mention we did sent an email in January stating we wouldn't pay utilities for the next two months because he took two months of utilities with the deposit which is against the law) since we thought this might make him take some action. And he did, just not what we thought. He came by the building on a Friday, 14/02 cut off the cord for the boiler so we(and another tenant) didn't have hot water or heating and had also turned off our electricity. I immediately called him but he didn't pick up, I sent him a message and his answer was: sorry no service for you. Electricity we turned back on, because the "electricity box" is in the hallway of the building. But, we were without heating and hot water for a couple of days until we could find an electrician. We slept fully clothed with multiple blankets, because it was so fucking cold. The lowest temp in the apartment was 6 and the highest 8 during these few days. We of course called the police but they said they cannot help us. We went to the Gemeente the next day, they couldn't help us. We even called our own Embassy and they, of course couldn't help us. But all of them said:"He can't do that, that is illegal. Even if you are not paying rent it is against the law." He then came again, the next Friday and cut the wires of the electricity. We called the police again, this time to just make sure they file another report. In the meantime we reported him to virtually every organization we could, but no one has still done anything. And before anyone asks, yes we are looking for a new apartment since November and hopefully will move out very soon. On what I need advice is: do we file a lawsuit which can take years and cost a lot(make too much for Juridisch Loket) or can we try with going to a regelrechter? I Googled a little and this seems much cheaper and faster than a typical lawsuit. It says that if the conflict is about up to 5000€ you can go to the regelrechter. We plan to ask for our deposit back and for him to cover the costs of the repairs we did. Our initial plan was a lawsuit but it seems hard to find a lawyer that is willing to fight for us and doesn't cost 300€ per hour. We fired our first lawyer because she literally told me"it's not an emergency if you have electricity" and "The temperatures will rise by the end of the week so you won't be that cold".
I was shocked when she said that.. Anyway, do you think going to a regelrechter is a good idea in this scenario or not?