I'm so sorry for your loss, and that his family are taking such a hostile attitude. One day they may understand.
None of us can live our lives with anything but what we're given at the time. You did what you could with very difficult circumstances, with an active addict, no support and young children to think of. One day I hope you'll see that, and come to terms with it. He had his battles and you had yours, and you gave him the dignity of making his own decisions.
Can I suggest you have your own memorial service, with some flowers, a picture of him and maybe read a prayer? You don't need his shell to remember and celebrate his good qualities
and the times you were happy. You might have F&F you can invite.
Really glad you can access counselling. I'm amazed about your studies considering your circumstances. This is something to be proud of.