I've been seeing a new partner for 4 months. He is 10yrs older than me divorced 5yrs after 20yrs of marriage. When we met he seemed very keen on me showering me with compliments, wanting to see me a lot and texting and calling often which he still does. After a month of dating I was holding his phone one night after we'd been drinking and a message popped up it showed a string of messages between him and an ex. He'd told me about this ex that she'd had a terrible time prior to meeting him as an ex of hers was sentenced to 12yrs for terrible crimes that she was completely unaware of and it turned her world upside down and he was sentenced whilst they were together. Everything she thought was true about this ex partner was a lie it resonated with him as his mother had also lied about the circumstances of his fathers death. It was a long distance relationship that he said had ended 6 months earlier she had also been with him when his mother died and they dated mostly during covid. He said their were extenuating circumstances given her past that meant he was in touch with her. I was surprised by the nature of the messages eg signing off with lots of kisses, saying he'd hope to meet someone as amazing as her. He has promised 3 or more times that he wasn't going to contact her again but when I've checked his phone (yes I know terrible) he's continued to be in touch alot. The most recent correspondence was saying he was having a wobble and saying he missed her. When I've confronted him he said he missed her as friends and the wobble was over me checking his phone and he said he would definitely not be in touch anymore. Intially I said unless he breaks off contact that's it between us but I've since said if he wants to be in touch with her then fine but as a result I would want things between us to slow down. He didn't want to do that and said he didn't want to be in touch anymore. On the face of it he's a great partner - he contacts me often daily morning and evening and lots of texts, arranges dates, has introduced me to his grown up kids wants us to spend Xmas together etc had shown a lot of interest in my life wanting to meet my daughter and friends he wants to be introduced as my boyfriend etc. I'm reluctant to embed him too much in my life given his contact with this ex I don't want to continue to check his phone, but also don't want to be a fool is he throwing himself into me to get over her? She's met someone else and lives over 3hours away. He also said they'd been dating quite some time before she told him she didn't think she could love anyone. So it's taken him a bit of time to trust that the relationship between him and I is real, he's said he thinks Im too good to be true he can't believe his luck etc. I'm just not sure what to do going forward? I don't want to check his phone as I've never done that previously in relationships, things between us is progressing but I'd like full confidence that he's not in touch with her? Or should I accept that even if he is contacting her he's not seeing her? Or should I forget whether they are in touch and just focus on him and I? I just don't want to have the feeling that I'm someone's plan b?