Thanks Jasmine, and I have no idea why noone uses discombobulated anymore, it's a VERY good word for what I feel.
My partner is very good at reassuring me, and this has already brought us closer, only a month in from the start. I definitely have a whole new level of appreciation for her, and she knows better than ever how important she is to me. Even after 13 amazing years, I realise now that we had stagnated, emotionally, and this has been such a wakeup-call for me.
I know that this will indeed be a long haul, and I hope I can see it through, I really do.
We have established some good boundaries on how they will act around me and in public, but they have no boundaries when they are together alone. I have chosen to not apply boundaries to their relationship, but I have re-established my own. And yes, I have started saying all of those things, and sort of keeping a written summary of how I feel, when I "feel" things, but I think I will start an actual diary. Thank you!