I'm having issues trusting my gf?

Some time ago, she confessed to flirting w/ another guy (by eye contact only) and apologized to me for doing so. She explained that the reason she did this was b/c she had a need that wasn't being met by me and she went to get that somewhere else. I forgave her and we moved on. Recently, she was emotionally distraught and told me she needed to talk to her ex-bf b/c only he could see the sadness inside her. Imagining my woman emotionally confessing to her ex-bf because of her belief that he has the ability to see something in her whereas I do not, tempts me to fear infidelity. Why can't she be emotionally competent enough to handle whatever she needs to handle in a way that doesn't compromise our relationship? I walk around fearing the next "creative" way my gf will seek to solve her emotional issues, how far her next emotional currents will take her beyond the bounds of our relationship, and the inevitable damage to my trust in her emotional integrity, and by extension, my trust in her. She didn't actually go through with the meeting w/ her ex-bf and later apologized to me for even considering it, but I'm still worried. I no longer trust this woman.