So yes, you can replace your income with passive income, it just takes a bit longer when you have more income to replace. If your willing to work for it, this is all possible.
If you average say $250/door/month in rental income after expenses, to replace your $20k/month you need to have 80 doors making this. You're not starting out with no money and trying to make that work, so this makes it a bit easier of course. At this point you should spend most of your time reading, learning, understanding everything you can about this business.
Start here: https://www.biggerpockets.com/... and read everything you can. Listen to the Biggerpockets podcasts, you can learn a lot about how other people have taken this journey. Your goal here is to learn, learn, learn just like anything else in life! Once you have a bit of knowledge under your belt, start looking at your local area and just watch the real estate market and see whats happening...see how houses are being sold, how quickly, what price ranges, what you are getting for that price range, etc.
The more time you can spend analyzing properties, reading, understanding the less time it will end up taking to move forward into your first deal. Decide what your goal is to get out of your current situation (5 years? 10 years? 20 years?) and make a strategy based on that. Write your goals down DAILY to keep them fresh in your mind, and always be working towards those goals. Try to impregnate this mindset in your everyday life...the more obsessed you are the better you will do with this.
As for the comment about getting a divorce...have a serious sit down talk with your significant other and let them know exactly what you are thinking, what your goals are, why you are doing this, and that they may have to put up with you being a little more absent for a little while so you can be a lot more available later. Any spouse in it for the long haul should understand and be willing to support this venture as long as you are willing to keep them in the loop of what you are doing...who knows, they may want to go in with you which would be awesome! Open communication is the key to happy relationships...