How to deal with incompetent or under qualified coworker?

For 3 mos. I've been sharing my new position with a coworker. I was offered the job, she asked for the job. My prev. dept mgr. recommended me for the role, so me, trying to be a team player and be helpful, agreed “to try and help out,” since our predecessor suddenly retired and I knew they really needed help. So we now work opposite days. I got a 30% pay increase but now have boatloads of work to do & never got any formal training. I'm trying to be grateful for compensation rcv'd but now i'm finding this work is more adequately at a 45-50% increased pay rate. However, it's NOT about the money it's dealing with this other person, who I'm having to train myself! I'm constantly texted, called w/ repeat questions bec they don't understand this or that and it's always during my personal time. Or bec they need help fixing mistakes, or simple shit like password lockouts or corrupting files or data. Not sure why they wanted this type of job, being they're so computer illiterate. This individual has corrupted every shared spreadsheet or electronic doc we use or has inadvertently deleted and/or duplicated data. Since we also have to share a dept. email, they've marked sev. emails as ‘already read’ but not responded to those new inquiries causing me to think they are being handled yet they haven't been addressed, causing even further delays! Another dumb shit example; they don't know how to unhide an Excel column! Instead of using the help menu, Googling or asking someone else at work, or trying to right click to see if there is an option that might work (IMO, Excel & most programs, right clicking is your bestie, I've even used that phrase before), instead, I got called and texted bec they're freaking out asking me why did i delete half a spreadsheet!

These past 3 mos. I've tried to streamline every single aspect of this job by eliminating redundancies, created forms and templates for all repetitive tasks, documented a lot of our procedures for (their) future referencing, and to improve record keeping overall. Lastly, i just updated 8+ yrs of CRM data and integrated this info. by migrating onto a new online format. Which I hope will reduce the amount of time spent on future projects by up to 50%. This service is usually at a company cost of $500-$2500 yet I figured out how to do this saving us that expense. However, this coworker is reluctant to use the new online method and somehow thought her continued data entry into excel would now ‘magically’ communicate with the online module and was shocked that all the data she'd typed was not showing up!!! Her lack of understanding of other procedures has already caused 3 disgruntled clients and i need to protect myself from being blamed for another's error(s) and try to be as transparent as possible. P.S. the new boss is out of commission (possibly seriously ill) so we've been running solo, err rather, really solo bec there's no managerial help to even turn to.

Loathe my new job and can't wait to quit, it's so incredibly difficult not to just throw in the towel everyday! I'm already focusing on my exit strategy, for sure! In the meantime, how would you answer their questions about stuff they should know or previously explained without blowing up? Y'all, I bout ready to loose my mind up in here! Thank you for reading this.