Why is she Txting her ex?

I've notice that my gf of 1 yr has been Txting her ex, an no I haven't stooped, I've physically seen her txt her ex, and it always seems like she's trying to make sure I can't see just by the way she holds her phone.

We've talked about getting married and are actually going this weekend to look at rings. She tells me every day how ice chained her life an how she thought she could never feel this way about anyone.

I just feel hurt, I know I should bring it up but it also appears like she's afraid to leave her phone around. I won't look at the phone ecause I think everyone needs privacy.

I just dont know what to do, I've been so hurt the past 2 days thinking about it. Ha anyone been in this position before and how did you deal with it?

Please no jokes, I'm looking for serious answers