I think that my ability to rebuild trust in my husband is two-fold. First, he had to demonstrate that he is trust worthy. Does he keep his word? Does he do what he says he is going to do? Is he reliable? etc. The real issue is do I trust myself? If I trust myself to do what I need to do then I am a lot more relaxed about whether I trust him or not. For instance, when I have developed a "bottom line" about what behaviors I'll accept or won't accept and am sure of the consequences and that I'll follow through on them I trust myself a whole lot more.
Trusting myself is probably the most important thing that I had to do. It's taken a whole lot of work in recovery to build that trust in myself.