I've just come out to most of my family within the last few weeks and it has been both liberating and heartbreaking. All of our friends have been so incredibly loving and supportive. Family has ranged from concerned to confused to indifferent, but mostly our relationships with them are still intact.
I've completely ruined my relationship with my Dad over it though. It's still very early, but I've disappointed him and he's ashamed of me. As a daughter who has spent her whole life wanting him to be proud of me, his reaction was devestating. I'm having to learn to let go of my need for his approval, and it's so hard. He's withdrawn his love and support until I'm 'done with all of it' meaning my poly relationships.
I'm not willing to sacrifice what I have with my husband and bf, I'm happier than I've ever been. That doesn't mean there's no pain at having to step away from the relationship I have with my Dad.
I can only imagine the pain you are going through having lost your spouse. I hope that your poly journey brings you much happiness though, because it really can.