I am afraid that it means that she does not want to have intimacy with you atm. That is why she believes that telling you about it would hurt your feelings.

You can offer her to sleep in the conjugal bed while promising that you would not initiate intimacy. Maybe she will be amenable. But do so only if this sort of arrangement would make it more comfortable for you.

Weight is very important in this society, and is part of identity for countless people. Therefore, losing 120 lbs basically makes one a different person - with a different identity. So if you married her at her heaviest, you are now dealing with a new woman, all of a sudden.

I wonder how she handled pregnancy and childbirth while being so heavy. You said that she had the baby 3 years ago and the surgery 2 years ago. That means that she was very heavy when pregnant, right?

That said, you report that things went south 6 months ago, while the surgery happened 24 months ago. Maybe then you are incorrect attributing her new behavior to the effect that the surgery had on her confidence?