Hi FG. Much like you, I struggle with the patience for DB and I've been at it for a long time now! Somehow, I just keep at it. However, there have been some improvements for me. These improvements really started when I stopped reacting to his behaviour and focussed on being positive and upbeat. I recognised and affirmed his positive actions. When my H became the 'alien' I kept reminding myself that there is no chance of having a rational conversation with someone who is irrational. I quit 'having a go back' and even defending myself.
Ah, the Alien phase. Yup, gotta say its like having a completely different person in the house! I sometimes think that he may even be possessed.
Anyway, if he is, its my demon too. I`m still going with the mantra "I`m sorry. Please forgive me. I love you. Thank you" Just fills me with positive energy and helps me release the anger.