This may not be what you want to hear, but what he is doing is violent and abusive, and it is just as bad as hitting. If nothing is done, this behavior will most likely escalate. Pushing alone can be quite dangerous. I am sure you realize that the moment he is doing these things, he is not paying attention to where or how hard he pushes you. You could land on something sharp, hit your head on something hard, or even go down a flight of stairs. This problem will not go away on it's own. I hope that your fiance gets help and finds a way to express his anger without violence, but either way please take steps to make yourself safe.