Just to touch on a few things to keep you going for the time being:
+ GAL = Get A Life: What this means is, getting out (or staying in) and doing stuff specifically for you, about you. It could be going to a gym, walks, cycling, going to the library, concerts, art gallery, extra curricular classes, spirituality, or reading, visiting with friends... focused on you, for you, by yourself.
This does a few things, most important of which it gives you time to process things, work things out in your heart and mind, enjoy life for the sake of learning and entertainment. These are things that help us grow in healthy ways. Second, it can add a sense of mystery and allure for yourself. It can draw our spouse towards us, as they may become curious about what we are doing.
+ you indicated SL: Based on the context of that paragraph, I'm assuming you are talking about love making? It is nice that she is including you. Of course, including you may be a tactic by her to keep you off guard. But that's paranoia talking. If she's involving you in intimate connection, it can help her to regain or maintain her emotional connection with you.
+ regarding the SMS she received that was work related. We talk about not mind reading, so this is just a guess. We can not know if there was any intention. She knows you snooped, she received a work related SMS and her phone was available for you to see and confirm the context of the message. Yes, paranoia could say it's a diversion to keep you off guard. It could also be an attempt for her to prove her claim. Or... it is all coincidental and all you have is a work related SMS which you shouldn't have snooped at.
+ regarding trust, there is no amount of proof that will MAKE you trust her. You will trust her when you trust her. Yes, that's very abstract but what that means is, once you finally CHOOSE to trust her again, you will. It won't be based on proof, it will be based on choice. Will you ever trust her again, like you did at one time? That is up to you.
So you now know what GAL is, so what kind of GAL activities could you do? Anything new that you've never done before? Make a longer list and then break that down to one or two things a week that you could do. How much is up to you, but do some.