Insecurities? Husband talking to ex

lil

I’ve been married for almost 3 years, I am from another country and came here because of him, we just had a baby she’s 5 months old. Ever since I gave birth everything went to shit, like 3 months ago I found out that my husband made a new Instagram where he didn’t follow me but follows his ex. They were like each other pictures at first I was mad because why tf would he make a new Instagram and follow HER and like all her pictures? But then I was like ok whatever, he changed his phone password and everything, like 2 weeks ago I needed to make a call and asked him for his phone, he gave it to me but was so nervous so I got curious and went and checked his ig dms, found out that they’ve been talking and he told her about how pretty she looked on one of the pictures, he asked her for her number and she told him “I won’t talk to you first, I’ll wait until you talk to me” I asked him about it but he started talking about other stuff, she doesn’t live in this country though but still. I feel so bad and upset I’m so tired of this, I don’t know if they keep talking but I have this weird feeling and I don’t know what else I should do