Hi SoapyBubbles
I am sorry for your situation. My own recent story is posted on this forum. I am in the process of sorting out my life now.
Being in a relationship with a heroine addict is extremely challenging. For me its been a nightmare & I caused myself a lot of damage. Yes on my part there was / is deep love, compassion, & caring.
Active addiction is destructive. Nothing good comes from it. From what I read above, you certainly have your hands full. From my experience, Its a vey slippery downward slope.
My concern for you is what you wrote - see below. The only advice I can give you is you need to spend time reading about heroine, addiction, denial, enabling, & co-dependency. You need to focus on yourself & develop a plan to make sure you are stable.
"I don't feel codependent. I've been through a lot in my life but have a good support system. This situation has made me feel lonely and sad and lost. I genuinely miss him and disengaging is really heartbreaking. I want to support him, and I also still fantasize about getting back together in the future, which makes me feel ashamed because it's so unhealthy. But as angry as I am at him, my care and love for him is unwavering."
I wish you all the best.