(((tryingtosmile))) - I'm so sorry for all that you are going through. I agree, it's not about the dog, that just seems like the straw that's breaking the camel's back.
I was in an emotionally abusive relationship for 20+ years with a functioning alcoholic, and I, too, was crying, emotional and everything else. A part of me KNEW that I needed to get out, but a bigger part of me was scared to death. Don't do what I did, which was turn to drugs and become an addict.
Now, several years later (almost 5 in recovery for addiction and codependency), I just found out that the XABF actually married ONE of the other gf's he had when we were together (it was a REALLY dysfunctional relationship, and I was a raging codie). Even though I don't want him or anyone like him, it stirred up feelings I was totally unprepared for.
I journaled about it and "talked" to several friends here. Today? I'm grateful for the person I've become and the crazy feelings are gone.
I've been driving all night, am about to go to sleep, but will check on you later. This IS an opportunity for you to get out, and if you don't feel strong enough about yourself, let us love you until you love yourself. In the meantime, one foot in front of the other, lots of deep breaths, and come here if it gets overwhelming.
Hugs and prayers,
Amy