7 months pregnant and found out my husband has been texting his previous girlfriend

I?m 27F, 6.5 months pregnant with our first baby girl and just feel like everything I thought I knew has completely changed. My husband (30M) and I have been together for 4 years married for 2 and we thought we were in a good place preparing for parenthood.
Very new to this Dating.mobi world so pls be patient with me. A few days ago, I noticed he was acting off, spending more time on his phone, being more distant. I chalked it up to stress about the baby, but last night while we were watching TV he got up to grab something from the kitchen and left his phone on the couch. A notification popped up from his ex, and my stomach dropped.
I didn?t want to snoop, but something just didn?t feel right, so I checked after he slept. They?ve been texting for months. She asked about the baby, and he replied something like, ?It?s all happening so fast, not sure I?m ready for this life.? I kept scrolling and saw her ask if he ever thinks about how different things could have been, to which he replied, ?Sometimes, yeah. Things were so simple back then.? After she replied him in a flirty way to calm him down. I am sick to my stomach. I confronted him this morning, and he admitted to texting her but said it was ?nothing serious? and that he was just looking for someone to vent to. He swears it didn?t go beyond texts, but I can?t help but feel so betrayed. I feel stupid for trusting him and now don?t know how to move forward.
I came to my parents? house, I needed some time alone to figure out my next steps. He?s upset about everything, but my trust in him is shattered, and I?m truly unsure how to move forward. I?m trying to stay calm for the baby, but I can?t shake the feeling that he?s not fully committed to our family. And why is he trying to get that comfort from his ex? Why would he feel the need to vent to his ex instead of talking to me, especially when we?re about to become parents? Need more perspective on this. I am so lost
TL;DR: I caught my husband texting his ex daily, exchanging good morning/good night messages, and letting her be flirty without shutting it down. He kept it secret, and I?m struggling to process the betrayal and figure out if trust can be rebuilt or if this is a dealbreaker.


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