Seeking Legal Help: My Landlord Teared the Contract

You cannot "profit" from this situation - the most you could achieve is getting financial damages covered by him. But there are several hurdles to be taken:
- You have a valid rental contract and thus the right to move into the apartment. If the landlord wants to prevent that, he has to terminate the contract (in writing and usually with a three months notice period). If you don't want to move in any more, YOU have to terminate the contract (in writing and with the same notice period - during which you have to pay the full rent).
- The only way to prevent it is a no-notice termination. The valid reasons for that are few and strictly interpreted. I do not think you have such a case here!
First, you need an independent witness. Then the behaviour of the landlord must have been such that you cannot be legally expected to move in any longer. This is the case if he e.g. threatened or defamed you or became aggressive - just bad manners is not enough.
And then, if you have such a case, you still have to show any reasonable effort to find another apartment at the same price. If you really can't (and can prove that), the landlord will have to pay the difference to the higher rent for a certain time (months rather than years, but the decision is the court's).
I believe all this is not worth the hazzle. If you differ, please get legal advice from a tenants' association ("Mieterverein", which you'd have to become member of first) or a lawyer (initial fee around €240, but you'll need one anyway later if you pursue the case).

My advice: It is always better to find a mutually acceptable solution, even if that means temporarily swallowing your pride. Both sides expressed an interest in not pursueing the rental contract - and your landlord already offered to pay some compensation. This is a great starting point: Ask him how much he is thinking of, then negotiate him upwards from there (but don't expect much more - Germans don't like to negotiate!). If you want to close the issue quickly, just accept whatever he offers.
Good luck in your further accommodation search - not all German landlords are unreasonable (I am landlord myself!) and he will probably find similarly bad words about you as you about him.

Dear beppi,

First of all, thank you very much for your detailed explanation and friendly advice! Can I have some follow-up questions if you allow?

He may still keep those teared-up contract papers. He made an "oral cancellation" of this contract by saying he is not renting it to me anymore. Is this contract still legally binding inow? (I can also tear my contract copy if necessary) I mean, am I required to move in, pay the deposits, and pay the first 45-day rents? (The contract requires a 45 days termination notice period from my side.) I am afraid that he will sue me for not doing these.

As you suggested, I would definitely like to talk to him. Is it necessary to make our solution done on paper, probably with signatures?


Bests.

Rental contract terminations have to be in writing - oral ones are void.
You could of course interpret his behaviour as an offer to mutually declare the entire contract void (which is possible, even verbally, if both sides agree) and then also tear up your copy. But the safer method (in case of later conflict) is to get this in writing - or unilaterally terminate the contract and keep your side of the deal (i.e. paying for 45 days from now - you do not need to move in and only pay for the part of the 45 days that are after the contractual start date!). Or you remind him that the contract is still valid and then find a mutual solution as described above.

I would add that contrary to what people might expect, the German court system is very slow (even minor cases can take years!) and inefficient. Many cases are judged poorly and get taken to a higher court. Even when one seems to have a definitely winning position, they can still lose. And then one is liable for court costs which are in the thousands of Euros. Like Beppi mentioned, finding an out of court solution is almost always better.

And it is NOT the place to try to teach someone manors. That would be an expensive proposal and they might not change their behavior anyway. Stay focused on your goal of having a reasonable place to live and forget the side issues!

Thank you again for your advice.

I did exactly what you suggested. I started to talk to my landlord. He asked me to make a proposal of how much money for compensation then I made one. He asked for some time to think about it. However, today I found out he blocked me on the chatting app.

I have my contract with his name and address on it. What should I now? Are the German police in charge of this kind of situation?

This is a private dispute, so the police would not help. (They can only help with criminal and public matters.)
I would write a letter (registered mail) to the landlord telling him that, after he did not accept your proposal or come with an alternative suggestion, you are now preparing to move in. Include a copy of the signed contract and ask for the date of the apartment handover.
I believe he will come back and talk to you then.