When someone breaks an agreement, it means that he or she didn’t really agree. What started as a reasonable discussion has become a fight. Now you are violating his privacy and he is accusing you of being controlling. Neither strategy is good for you as a couple.
I suggest that you both take a deep breath and go to the root of the fight. This will be difficult. It will require you both to forgive what was said during pointless fighting. It will require you both to decide that your relationship is worth having some difficult conversations about trust and boundaries.
Put the conversation about this particular woman aside for a bit and talk in general terms about what each of you believe are appropriate friendships and what you want from each other when you are both home. Then talk about why this particular person feels threatening to you and what he needs to do to reassure you. Do your best not to blame or accuse. Instead, stay with how you are each feeling and what changes will make you each feel better.
Conversations like this may be difficult, but, when they are done well, agreements are real agreements and the relationship becomes stronger.
I wish you well.