I saw some messages between my fiancé and her sister about my daughter (her SD).

Some background. I have been with my fiancé Jade since my daughter Katie (8) was 2.5 years old. Katie’s mother Ari (34f) left me when she was almost 2 but lived with me for about 6 months until I finally told her she had to leave. Our relationship was toxic, she was awful to me, & has used our daughter against me for a very long time. Jade encouraged me to get a court order & I was able to get 50/50 legal custody even though I do more for Katie than Ari ever has. Ari has always been awful to Jade, Jade has her blocked on everything & only communicates with her when it’s necessary which is rare. Jade & I have a son who is almost 1. This is the long story short.

Jade was out for the day with her friends and I was using her iPad to stream a movie to the TV for my daughter since her iPad was in Jade’s car. It was dead & when I plugged it in texts started popping up from the night prior, one of which said “you ever think maybe you should just leave him?”. I know it’s not right to go through phones but this obviously caught my attention & I’ll admit I snooped. Jade responded by saying she could never do that to Katie & loves us both. But she also said at some point in the conversation that she “sometimes wishes [I] never met Katie’s mother” & essentially that Katie was never born so she could have a nuclear family with just the 3 of us. She follows up by saying it’s not because she doesn’t love Katie, it’s just because of how hard her mom makes it. She talks about traits in Katie that are obviously from her mother & how she hopes she grows up to be nothing like her. She talks about how sometimes when Katie’s gone she gets anxiety the night before/morning she’s going to come back because she knows Katie being here = potential drama from her mom. Katie adores Jade, she has asked to call her mom, always wants to hang with her, Jade always plans cool things for her & volunteers at her school. I know they love eachother & I’m not even mad at Jade because I know she went through a lot with Ari because I went through at lot with Ari and in the beginning I know I could’ve done more to protect Jade. The list is long of awful things Ari has done & the court order details prove that. I know I shouldnt have gone through the messages but seeing someone text the woman you want to spend your life with inquiring about her leaving you will make anyone panic. She is the happiest, most bubbly, kindest person I know & can brighten anyone’s day. I hate that she feels this way. I guess I just want to know if this is something I should address? How would you feel about seeing these messages regarding your child?