I'm writing this on my 2012 MacBook Pro that I've kept running all these years. I share your pains!
First, your computer's keyboard can be replaced/repaired by an authorized repair shop or by Apple. It will probably cost less than $100 which is sort of worth it if it keeps your machine running. I can recommend an outfit in New York that will work with you to ship the machine. PM me if you'd like their contact info.
Second, you could try using the Apple Magic Keyboard. This connects via Bluetooth and can be charged with an iPhone Lightning cable/charger. Apple also makes a remote Trackpad that connects through Bluetooth. Both of these devices will work with an iPhone, iPad or probably some other non-Apple devices.
Lastly, and I know you don't want to hear this, perhaps it's time to start considering a new computer. Consider this: This laptop of mine cost about $2,500 in 2012. The CPU was the maximum Apple offered and I maxed out the RAM. It was, I think, the last Apple laptop with a SuperDrive built in, which was why I bought it, (a feature that would become obsolete within 6 months of the purchase!).
But here are the economics. $2,500 ÷ 8 years (roughly 3,000 days) = $0.85 per day of use. If you're like me, you use your computer at least 4 hours and as much as 15+ hours every day. For 85¢ a day. Since I use my computer to earn my living, that's better than free because the capital investment is tax deductible.
The new machines have even fewer moving parts than ever meaning that the computer should last a long time. And if you're like me, you can keep the old machine as a second computer.
This year I bought a new MacBook Air to be my primary computer. Once again, I bought the top of the line and maxed it out. It cost me about $2,250. Good luck with whatever course you choose!
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