I think you probably do need to share your feelings. Either with work (which isn’t the end of the world; they are required by law to make ‘reasonable adjustments’), or with your GP, who might be able to help, or just with someone who you trust.
Starting with us is a first step. Carole has been pretty much where you are (and I didn’t know she was a teacher! Amazing sometimes that we feel we ‘know’ each other and yet don’t know something as basic as that!) so her advice is sound.
MS is an absolute swine for making you lose confidence. I was OK for the first few years after diagnosis. But my last 6 months at work were a bit of a disaster. I essentially didn’t do much in the way of work at all. In the end, I went on long term sick leave and finally was made redundant. I was a consultant for local government. Mostly I wrote and delivered training courses, but also did a few other bits and pieces, to do with writing policy manuals and helping out colleagues with job descriptions and person specs. If I didn’t work, my little department of the company - me plus another employee and sub-contractors - didn’t make any money, hence redundancy!
I actually went for a job interview after that for a job that was about 3 rungs lower than I had been doing and didn’t have the confidence to do a decent interview. That was 12 years ago. I’ve not worked since. And it does make you feel lousy, not being confident about things that you really do or should, know inside out. It’s taken me years to regain that confidence. I’m 21 years into MS me.
I still have cognitive problems. Words fail me. Multi-tasking is impossible. I simply don’t hear what someone is saying if I’m concentrating on (for eg) writing on here. It drive my husband nuts. He talks and I have to say, ‘I’m sorry, could you start that again, I didn’t hear a word of what you said!’ I can only rarely remember what I’ve read. Even things I’ve written on here, I’ll come across something, re-read it and I’m stunned that I wrote it!
But - I am still me. Still opinionated, still bossy as hell, I still read a lot, regardless of memory, I still do the crossword, still know some things, often facts that I didn’t even know I knew. I still swear like a trooper and shouldn’t be allowed contact with children on account of it. My husband and my good friends still love me. I can still write.
And I’m quite sure that once you regain a bit of your normal confidence in your competent brain and fluency with the language you will be OK. You can’t teach if you don’t have either, so I know you still have it. You’re just a year into diagnosis; it takes time to get your head around life with MS. You will still be you. You will once again be confident and strong.