Help me fix my motorcycle

Hello, my name is Kruno, since I was a little kid I dreamed of having a motorcycle, but I never got it from my parents because they are very much against it and we are not so wealthy. I owned a moped for a short period of time when I was younger a few years back (my brother gave it to me as a gift), but it was in pretty bad shape, and it was on a stand most of the time, in the end I sold it for about 50€. When I finished high school I found a job and started working. After about a half a year I got a permanent employment contract, and went to get my driver’s license, after that I collected some money but that wasn’t enough, so I went to the bank and took a loan. I was searching for some time and found a bike I like, it was a Duke 390 from 2016 and it was pretty close to 30 thousand kilometers, that’s about 18600 miles. I went to look at the bike alone since I didn’t know people that have experience. The only person who had experience was my dad and my brother who was a rider before, but I didn’t want to ask my dad to come with me because we have a really rough relationship nor my brother because he was always telling him to talk me out of it, and that he would blame him if something happens to me. It’s registration was expiring soon so I asked the guy to lower the price for that amount. We settled for a bit less than 4000€. When I went to register it, first problems occurred; the mirrors weren’t original so I had to buy a new pair, the rear tire was bigger than it should be, and the original plate holder was sawed off to some kind of DIY short plate holder. So I had to buy all of that and spent quite an amount of money. After about two months of riding I was cruising around as usual and all of a sudden my engine broke down, I knew it was something bad because I heard grinding and cracking through my helmet. I pulled over to the side of the road and took a peak at the engine and saw the engine case had a crack around the engine sprocket; I didn’t want to try and start it so I don’t cause anymore unnecessary damage. I called my brother and he came with a small van, fortunately it was just big enough to fit the bike in. As we pushed the bike it was in gear but I didn’t have to pull in the clutch, I knew the gearbox was broken at that moment, we loaded it in, tied it up and went home. My dad was furious. In the next week I took the engine out and opened it. I was devastated when I saw the damage done on the inside, the piston rod rode, damaging the crankshaft, making two more holes inside of the engine case, the piston slammed into the header, bent the valves, and the list goes on... At that point I realized the engine has become too expensive to repair and the only thing I could do with it is sell it for parts (what was left of it), or scrap it. Later I was told the engine was faulty before I bought the bike and that the previous owner didn’t take good care of the bike. I was searching online to find an engine for sale inside the country but with no luck. I found some engines outside but that was too big of a risk for me to buy them because I was afraid of getting fooled. I asked a local KTM authorized service how much a new engine would cost and it was more than I paid for the bike. I don’t have that much money... If you could help me I would be very grateful, thank you from the bottom of my heart.