Engagement Worry

My boyfriend of four years and I just got engaged a month ago and we haven't told many people, just mainly his family. I have put off telling me family that we're engaged because I really scared about how they will react. They aren't all that supportive in any of my endeavors and they tend to view things in a negative light. I want my family to be happy for me and supportive but I feel like when I tell them it will be as if I told them about something mediocre. In addition to this my fiancé still hasn't asked for my father's blessing... we have never had a great relationship but I think it is a good sign of respect. It might be unnecessary though.

Any advice on how to handle them reacting poorly to the news?