Hi Jenny, you are doing so well, there is such strength in your post along side the sadness. What it boils down to is it is hard to let go of someone you love but I found it easier to say I was not supporting the addiction, I refused to have a relationship with it, I would not be dragged in and let it claim another victim. This may not work for you but I found it helpful. You need to keep protecting yourself and your kids which you seem to be doing a good job of.
You are obviously a strong capable caring woman who is doing her very best in a very difficult situation. I get exactly what you say about being a single mum, sometimes just having someone to talk about worries with your children or a tough day at work can be worth its weight in gold however there are other places you can get that. In my case I use a counsellor but there are lots of mum’s groups or other social groups where you can make that network to have support around you and you don’t have to tell them everything (I know it can be hard when you have a cg in your life and worry about being judged) even letting out the everyday stresses helps enormously as it gives you space to deal with other things.
Keep on keeping on you are doing great, Lily x