Am I fair not wanting my girlfriend to still text her ex-bf who Joined the army?

girlfriend and her ex-bf decided to break up since he was going away to the army for basic Training in 5 months and didn't want a long-distance relationship. Their relationship was healthy but not perfect. I somewhat suffer from being a nice guy and have trouble setting boundaries. I feel it's not okay for them to be talking since we are dating now, and this could cause issues in the future when he comes back from basic training. I have allowed all of my ex to still talk to their ex-boyfriend since I didn't think it was a big deal, but every single time, it comes back to bite me in the ass. I have set 3 boundaries in my head, but I am unsure about them.

1. No talking to exes or anyone you have been sexual with.
2. No hanging out with the opposite sex alone at their place. I have zero issues with this in a public setting, but I have allowed this in the past, and it didn't end well for me.
3. No cuddling with guy friends.
I am not currently friends with any of my exes. I do not mean to be controlling or Sound like it. I have tried to be in what I thought was a healthy, trusting relationship but learned if I don't set boundaries, then things can happen.
Updates
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Issues I had in the past. 1. My Ex would wait for us to fight to take advantage of girls I dated in the past. 2. Cuddling turned into having feelings for said friend or Friend taken advantage
Am I fair not wanting my girlfriend to still text her ex-bf who Joined the army?
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