For the ex-spouse of an addict, having to let go of an addict is like death without a corpse. I used to say that to other people long before I started reading that phrase on SR. Now that you're not living with your AXH anymore, and you are not experiencing his addiction drama, seeing him is going to be difficult because you are seeing him outside his "drama orbit".
Someone also said that people get addiction to the "addiction drama", that's what it's like being a relapsing codependent. So essentially, your AXH is triggering your codie tendencies.
I have the same problem. Lately I have been thinking of what things were like when things were good between STBAXH and me. But most of those memories are memories of plans I used to make with my addict, we had so many plans for the future, which never came to pass. My addict was never in any position to be responsible in a relationship. He could not be responsible for love. He wanted to be, I'm sure. He probably did love me very inadequately. I know that I still love him and I always will love him. I am also angry at him, sad for him, and hope in vain for his recovery... but I can do nothing about those feelings expect to just feel them.
I don't think there is anything wrong with you having dreams, but you do seem to have a good relationship now, and I'm happy for you.