I think you are making a good choice to say no until you guys sort this out. I'm kind of worried that his reaction to your 'no' is to start talking about what everyone else is going to think, rather than realizing that what he did was way out of line and he is in danger of losing you if he doesn't shape up.

The 'what will everyone else think' is a really typical thinking pattern for an abuser. It sounds like he really has some thought and behavior patterns he needs to get a handle on before he gets married.

As you are experiencing, these things tend to get worse with time. I hope it all works out for you -- and I would not want a surprise proposal, so I don't think there is a rule about that