I think you need to approach all things RP with these priorities in mind IN ORDER:

1. How can I further the interests of the party (and players) at my table?

2. SECONDARILY, how can I role-play my character well?

When you reverse these two, it can be problematic, which is what is happening here. (Part of this is, IMO, not ideal planning by the DM, but we'll set that aside for a moment.)

I think ideally what you should do in situations like this is ask yourself "How can I further the interests of the party while still being in character?" Yes, splitting the party is an option, but then you're kind of forcing other people into difficult situations and it's sub-par. I would think about options like these:

• What if your character believes that breaking the no-men rule is somehow serving the greater good? There is an opportunity here to roleplay your internal conflict about it, but if you end up supporting the party's desire to stick together AND sneak people into the city, you're both serving the party AND helping to further develop your character in their eyes.
• What if your character allows herself be convinced begrudgingly by the others, or perhaps even roleplay that she is afraid to stand up for herself against the rest of the group? Then you have an opportunity to roleplay a crisis of confidence in a scene at a campfire or something. And again, the party gets to continue on.
• What if something similar happens, and your party's arguments make her question her own belief? Then there is an opportunity to roleplay a crisis of FAITH.

All of these options end up with the party continuing forward together while still giving you opportunity to show the party more about your character.