No Need to apologize.
I apologize for the need of a memory refresh, did we change files together on your installation?
If all we did was within the admin panel, then you can update with no problems.
either way, a safe way would be:
1- backup your database
2- backup your theme files (and all WP files if possible)
3- download the new files from theme forest
4- upload the new theme folder to the server
5- activate the new theme
6- do a quick check on the website
7- update to WP 4.3
8- do a quick test on the website
If anything appears to be broken, kindly take screenshots and report them and we’ll fix
Please let me know if you need help with any of the previous