Hi Maca, nice to meet you,
I think it's good when couples can communicate together via a blog but out of respect to LR I won't keep responding unless she comes on and says she's OK with it.
I will say that it sounds to me like you never worked through all the pain when you first found out about their affair. You thought you had no choice but to accept GG and that has just festered under the surface all this time. I found it much easier to come to terms with my partner's other relationship after he said he would give it up if I couldn't deal with it. When I got to that point he did try and give it up, he gave it a really good go but it seemed that just his honest attempt to try was enough for me to be able to turn around my coping mechanisms.
I sense you feel like you were the only one of the three of you feeling the pain over LR's relationship with CG. By you moving out the pain has been shared. Maybe this is your starting point? I don't know, other people's issues always seem more clear than one's own.
I wish you all (all three of you) the very best.