to disappoint someone by telling them the unpleasant truth about something or someone that they had a good opinion of or respected

I hate to/I'm sorry to disillusion you, but pregnancy is not always wonderful - I was sick every day for six months. 我不想打破你的美梦，但是怀孕并非总是美妙的事——我当时有6个月的时间天天都恶心。