Announcing to unsupportive family

So fiancé and I are pregnant. We're both over the moon excited. We've been together 7 years and getting married next fall. I'm 23, he's 25. I think my family will take it moderately okay however we're concerned about his mother. Once before when she thought I was pregnant she was FURIOUS. Granted this was two years ago but every time grandkids come up she is less than thrilled to say the least. His aunts/uncles and grandparents will be fine but does anyone have advice on telling momma? I kinda want to do something fun and like Christmas came early this year to try and make it a positive situation from the start but then again I feel like I may need to have a serious sit down conversation instead. He's on board with whatever I pick. It's hindering my excitement because I'm so anxious about her.