You really should pass most of the responsibility of choosing on to her, just because some shit happened to her it doesn't mean she is very psychologically fragile. But make sure she understands the risk and some of the dynamics of the effects. For example, I think it's important for most people to learn the dynamics of the come-up, that anxiety, uneasiness and some body load are possibilities.
You can also give a lower dose, some said one tab but if they are good tabs eating only half and boosting with pot is a very good introduction to psychedelics. This kind of dosing is the most common in the rave scene where I'm from. By the way, definitely have pot available, it can make a rough trip amazingly smoother IME.
Other than that just make sure you follow the general recommendations about first times (music, privacy, possibility of staying either indoors or outdoors, etc).
And if she sees you've made an effort to give her a good experience I can't understand how she would be upset at you even if the trip goes wrong.