It's very overwhelming at first. We've all been there, and overwhelmed for our own reasons.
But slow down, take it one step at a time.
First, things like food, vet stress, and infection can all raise blood glucose levels. So if you address any of those, your kitty may not even need insulin in the long run - which would be the ideal case! So make sure those things get addressed as needed, and see if it drops her glucose levels enough to stop insulin.
If she does need to continue receiving insulin, there are ways to handle it even if you're working long hours. Squaliesmom mentioned finding a vet tech in your area -- this is an excellent suggestion. First, see if there are any vet tech schools nearby, a student would be glad for a few extra bucks plus get some hands-on experience. If there aren't any schools, ask your vet or do some looking online to see if any techs will make house calls in your area. Another option is to find a pet sitter who is knowledgeable enough to do insulin shots. There are many who will, since it gives them a bit of an advantage over other sitters.
There are options to make this work!
For now, just take a deep breath, and start to read and absorb all the information here. Ask questions. Don't be too hasty in making any decisions. People with all sorts of work and family situations have found a way to take care of their sugar cats, and there is quite a range of situations on this board - so wherever you end up going next, you will have people here who can provide advice.