I am sorry you are having a rough time. Impulsivity is a big problem for me as well. My therapist has given me several tools to help me as well, but I agree with you, practicing them is a different story. I like the idea about saving emails in a draft. I have gotten into trouble with email more than once!
I am glad that you are looking into working on your relationship. My husband and I have gone to marriage counseling and it has helped. Is moving even a possiblilty? Have you ever looked into light therapy? I know it is hard to be content. Try to look at the positives in your life and focus on those. I know that is easier said than done when you are in a tough place.