Found 1.19 btc on old hdd, how to sell.

Hello I found an old intact multibit wallet from 2014 with over 1.1 btc on it.

I managed to open it up and resync in multibit (took a while) and then export the wallet key to an electrum 3.x wallet after some serious fiddling around on the computer all night... and from there to a newest version electrum wallet, so it now sits there safely.

My financial situation is such that i really needed this and it came like a miracle, I want to sell it off at least 60% of it right away, but how do I sell it for the least amount of fees to my national fiat currency (Swedish kronor) without the tax authorities being on board accusing me of laundering money or something and so that i pay my cgt correctly or will that be arranged automatically?

They are doing chain analysis or what it's called and people do get in trouble for it all the time.

I haven't gotten it from anything illegal, but back in 2014 when i bought it from a major swedish btc trading site, i used it as a payment method for some bad personal-medical habits that I have since stopped doing, and i want to pay the capital gains tax and everything in accordance with the law. But I wonder if there is some way to get around the big fees that the well known user friendly trader platforms have? Like is there some way that maybe i could just get it direct contact with a person who wants to buy a lot of btc and give med swedish kronor and sidestepping trading platforms alltogether but making sure they are not going to rip me off somehow?

edit: please I am not going to sell btc to some random individual that just makes contact with me online, i've gotten several chat messegas since i posted this, just stop, I'm not going to sell you my btc or "validate" my wallet... stop it

edit2: thanks everyone who answered with good ideas, I have a better idea on how to proceed now, thanks to your answers, probably i will sell a lesser part of it than i originally wrote thought short term, maybe 25-30% or so, which is still not bad money in this case, make sure bank and tax authorities understand where it comes from and such, use some service from where i can use maybe 20% of it as a payment method and then hold on to the rest for the future... or something like that. This is all very exciting for me but also a little scary.