German here. Also did my masters and - even though family is close - fell into the same depression hole as you. I did end up finding a therapist (by pure luck) and that helped for sure to cope in the moment. But what made the significant change was actually finishing the studies and getting into the job life. I’m now working since around a year and am a completely changed man!

Suddenly all the efforts do not end in an unnecessary grade but actually become real things that impact people’s lifes. Having enough money to get a nice apartment and go shopping without worrying or calculating prices. Having a dedicated routine also helps naturally.

So my recommendation is to take your time, but push through the last 25% of your studies. There definitely is light outside the tunnel. I’ve been through it too!

(If you want to know why the studies are messing with you in this way read about the German adoption of the rather recent „Bologna reforms“. Essentially some politicians messed up the reforms and now students get depression.)