Your situation is reminding me strongly of PollyPocket's current journey
, but from an opposite perspective.
Some of the difficulties in adding a third to an established marriage or relationship seem to be about power. It sounds like A has exercised her power in a way that makes it harder for you to trust her, and feel safe loving her. After all, a break in your 3-way relationship means you
are out in the cold, while T and A are still together.
Of course, A is probably feeling threatened and scared as well, and more than likely that's what made her feel the need for a break.
If you work as a team and don't allow some competitive wall to grow between you and her then it's quite likely your bond will grow deeper - if in a totally different (and maybe surprising) direction. Keep an open mind and try to be flexible
This and the rest of GS's post sound like great fundamentals to follow in making this relationship work.
Best of luck!