It's really difficult to choose from one of those options, but in any case I would say both 'rude' and 'inconsiderate'.
There are several points:
Not telling the girl he was planning to be married.
Not informing you of the relationship or the details of the past relationship.
Keeping in touch with the girl if there was a past serious relationship with her, and not including you in the friendship if there was not. If the texts were excessive, then that is an issue. Really, I think if any text at all, meaning she has his phone number and knows that his phone is private, then it's an issue, or it would be for me. To me, giving someone access to you to chat whenever and wherever you are, with family, in your home, at work...is a bit intimate. Why can't she just send a letter or a card. What is the point of keeping in touch? At that level? That would be my question? He has had more than enough time to end past relationships and move on from them.
Keeping photos on his computer that you had to come across by accident.
SURPRISE visit, without your consent, putting you on the spot.
Not providing you with a trusted third party translator of your choice for the visit, or choosing to speak in a language that you could understand when talking to this woman.
OK, it is too late now. But in ANY LANGUAGE, turning your back on your husband and walking away from the HUMILIATION of having to stand there with your baby while he carries on a conversation you cannot understand and cannot possibly be included in, needs NO TRANSLATION.
Since this was a surprise visit to an ex-girlfriend, I think you were entitled to do this. It is too bad you didn't think to take the car keys and drive away. Let him call a cab or bum a ride. It will give him time to think.
However, hindsight is 20-20.
Your husband sounds controlling and secretive.
You cannot control that he behaves like a selfish boy who is not married and cannot think of his wife's feelings as considerately as he considers his own. Therefore, you must double up your consideration of your own feelings. I'm not saying to have a hissy fit where he can point at you and say you are 'always angry'. Just saying to walk away from or refuse to participate in any situation that is humiliating for you.
Your feelings and intuition are not to be questioned.
They are correct in this situation.
He will try to pass it off as misplaced jealousy.
In my opinion, he is full of it.
You don't take your wife and lover and mother of your child to see a female friend, especially someone you might have been involved with in the past and keeping photos of them and wife does not find out about the woman until marriage. And then have a visit in a language your wife can't understand. Rude!
It's possible that he hasn't got over her, and he was showing off in a vengeful way to her, saying look I got married, I am not as bad as you said I was when you dumped me, look I even have a child and I can afford to come home for a visit. In that case, we can see from how he treated you in this situation, why she dumped him. I don't know the story behind it, but there is some literature that suggests that men are prone to a 'winning complex' when it comes to women. If they are dumped, they will go to great lengths to try to keep winning that woman over, even years and years and years after being dumped and obsess over 'having the woman'. (My H included.) It is not love, it is a reaction to rejection.
You can make this work in your favor. Someone recommended to me the 'Why Men Marry *****es' and 'Why Men Love *****es' book. It has to do with uncertainty (within limits) and a 'chase' and looking out for yourself and your feelings and interests and finances as a woman. If they are busy and happily occupied 'chasing' and 'pusuing' you to get your continued attention, they will not have time for these outside obsessions.
It's not the girl they want, and in most cases probably the girl doesn't want them either...they just want to have some control over the other woman because of the past rejection.
It's just a theory, based on readings about the differences of men and women and my own H's experience with some girl/woman who dumped him (actually several
I would be humiliated and concerned too. I would use the energy and anger of humiliation to make changes in myself so that this sort of thing would not happen again. I am worth more than that and so are you.