I just recently came out to my family. Actually it's still ongoing.
I'm in two very serious long term relationships and not being out with my family was causing tensions with the partner they didn't know as my partner. I also live very far apart from my family (6 hour flight) and we aren't close, I speak with my mom every few months, and everyone else maybe once a year, and we see each other every couple years. That being said, having one partner excluded from something that is such a big part of my past wasn't feeling okay. I want my family to know about my partners and I want my partners to be able to know my family.
I told each immediate family member on their own, I started with a couple easy ones, my dad and sister, and then went for my mom. My dad (my parents are divorced many years ago) and sister are both very easy going and accepted it immediately. My mom was another story and I knew it would be. She is very religious, and very emotional, but also very loving to me (not that those are exclusive things) so she was soft and accepting of me, and my partners, while not accepting it on a spiritual level. I called her and spoke with her for an hour on a Thursday, then gave her the weekend to process it, and called her again on the following Tuesday. This time was with her even more religious husband. Surprisingly they kind of just accepted it. They said they don't agree with my lifestyle but they accept me as I am. I spoke with them about possibly visiting over the holidays, with all three of us, and they said that we were welcome in their house to come for dinner, and I would be welcome at the family dinner.
After them I told the rest of my extended family members and everyone accepted us to varying degrees so far. I still have one aunt and one uncle to talk to, and mt Grandfather who has dimensia so I don;t even know what do do there.
I was wary of this for a long time, but it was really important to my partner who my family didn't know, and through that it became extremely important to me. Having an imbalance between my 16 year relationship and my 4 year relationship isn't working for us any more so breaking down these barriers that seemed unimportant in the past is becoming my top priority.
One thing I would say against what Evie explained, based on the information provided, is that we should consider whether it's right to make it anyone's burden to tell someone else. Generally I didn't feel it was okay to ask my mom to tell my Grandmother or aunts or her husband while she was still processing how she felt, but she insisted she should be the one to tell her husband. I was clear that I would do that work, she didn't have to do it, but she wanted to. Lots of situations would make this divide and conquer approach make sense, existing family dynamics that make things more complicated, communication skills (doesn't it always come down to communication?) or closeness of a relationship, but I think it should be used with caution. It could easily be avoidance on our part.