I've been thinking about this since I read it this morning Smelena (sorry if I typo any - the keyboard is being incredibly slow for some odd reason)
A good teacher will always be remembered, and whilst they cannot ever be replaced, they have set an example for those who step into the oft large shoes to takeover.
You have a benchmark for future SEN Teachers, you know what can be achieved with the right support - lots haven't even had that! You have coped admirably thus far, and whilst you may be in for a brief storm surge I am certain with you at the helm the replacement SEN will turn out wonderful for your two. Lets hope too much hard work isn't undone, and Good Luck!