Should I be upset

My husbands ex gf is always posting pictures of him and their child from back when they were together. Just him and the child . He claims they don’t have a good relationship and that it’s strictly co parenting but I feel like she’s always pushing to be super friendly. He says he’s not at all with her but I feel like why is she comfortable enough to post pictures of him and the child when they were together back in the day. She has done things like Lied about them having sex trying to break us up… posting all on the internet digs at our relationship saying little did I know last Valentine’s Day she had him….even though we’ve been together for 6 years. When his mom posts pics of him she’ll put the heart eye emojis. I can’t stand it. it just infuriates me she thinks she’s so relevant. She’s like the “I had him first” type of chick. He says he’s not nice to her but like idk. I never hear them talking. She has tried multiple times to be in my business and try to come over but she finally stopped trying when right before that she told the child she didn’t have to listen to me and I’d never be her step mom… I just want her to stop posting my husband. She’ll do it on every occasion. I tell my husband and he just brushes it off saying it’s just social media. Like he’s ok with her posting pics. I’m just mad I almost feel like the second time around chick when this girl has caused so much trouble in our household and you’re still ok with the dumb shit she does… why don’t you have my back makes me feel he’s nicer to her then he claims to be if she’s doing all that .. thoughts ? He says he doesn’t like her at all and can’t stand to even answer the phone when she calls but seems like she finds any excuse to call. We been married 3 years now I thought it would stop. She needs to be out in her place and he says he does but I’ve never seen it happen