I went and reread your original thread.... sounds like things have not progressed well in the last couple months.
Sarah still only wants you and Tom to have sex when she is also in the bed and touching both of you? Most of the time here, I see recommended for triads, for each couple to have sexy time one on one (as well as 3ways, if you all enjoy it, but requiring it seems a burden and unrealistic). Sara and Tom, you and Tom, you and Sarah. Group sex required every time will hamper spontaneity and bonding between each couple.
You said earlier Sarah works a different shift than you and Tom... A couple working different shifts is going to have trouble feeling tight and bonded. Never mind adding another woman into the mix, monopolizing all her husband's free time.
Even though you have excused yourself from spending less time with Tom and more time doing things on your own, or with other friends, I can see why you getting so much of Tom's time would lead to feelings of jealousy on Sarah's part. It makes it seem that the new woman is closer to her h than she is! Not an equal, but "greater" than her in the triad. And that really burns. You might seem like a usurper to her. I know if my gf spent 5-6 nights a week with her bf while I was at work, slaving away, I'd feel jealous, or envious at least.
Adding in that you confessed to cheating on Sarah and fucking Tom one on one several times without her knowledge or consent (did you 2 ever confess that to her?)... yeah, it seems to me you need to gently back off just a tad and allow Tom to be alone now and then, allow her the luxury of not imagining your daily cuddles and closeness when she's on her work shift.
Love withers under constraint; its very essence is liberty. It is compatible neither with envy, jealousy or fear. It is there most pure, perfect and unlimited when its votaries live in confidence, equality and unreserve. -- Shelley
me: Mags, 58, living with:
miss pixi, 37, who is dating (NRE):
my bf: Ginger, 61, married to:
Robin, 60 (mono)
and dating (NRE): Carla and David, married couple, early 40s