You’re on the executive team – you’ve clearly earned this, now please don’t demean yourself by being petty or passive aggressive.
I would speak to her directly – which is something that should have been done the second time it happened. (Chalk the first instance up to ‘Everyone makes a mistake now and again’, but you’ve said that it’s intentional.)
The good news: iis highly unlikely that no one else has noticed this behaviour; your colleagues know how to spell your name, and she is conducting herself poorly. In my career I’ve seen that sometimes long term employees are given leniency when they act in appropriately, as your colleague has been doing. You don’t have to stand for it, but you do have to work with her, and it is in your best interested to keep it professional and above board.
Becaus this has gone on for quite some time, it may be best broached as a conversation. Next time you get an email from her while you are in the office, ask directly, in a friendly tone:
“[coworker name] you always spell my name. As ‘_abcd_’ – why is that?”
She may hesitate, pet tend not to know what you mean, or give you some excuse. Listen to her answer and then reply with “I’ve always wondered, because my name is actually spelled ‘__thisway__’ [if you were names after anyone special, or it’s a regional spelling, mention that too]
Your goal is to remain professional, kind, but assertive. Once she has this information and no excuse to misspell your name again, her behaviour is likely to change. If it doesn’t, mention it each time.
Now, the reason this behaviour bother you so much is due to the power struggle you are experiencing. You mentioned that she treats you disrespectfully in other ways – you need to deal with this head on in order to get past it.
Without knowing the full history of your employment and this relationship, it is difficult to give concrete advice. Different situations warrant different approaches. It could be useful for you to spend some time uncovering why she behaves the way she does. Does she feel threatened, slighted, scared that she may become redundant? Was your relationship always difficult, or can you pinpoint something that happened? Can you build a stronger relationship with her by partnering on a task, or asking for her input on something?
Remember: it is possible to be direct and professional without being perceived as a weak or a complainer. Regardless of your age, you deserve respect.
Last, do you have a mentor? It may be helpful for you to find one who can help you navigate these types of situations. They are not unique, and it can help to talk to someone who has been there, or seen similar before.
Good luck & feel free to reply if you have any questions 🙂