I understand the pressure OP. I find it very difficult to come out. At work, in a previous job, two people i thought were friends got onto the topic and one said she hated working with lesbians because she had once and one of them "stared at her tits". Due to that one fucking stupid comment I ended up not coming out at work in an office of about 40 people and it just felt horrendous.
With family I actually wrote a letter. it did not go well quite honestly, but that was a long time ago.
TBH things are so much better now and they get better every decade, but I think anyone's fooling themselves if they say there isnt still judgement, as you've discovered (your uncle). However... this is my thought: anyone who gives that kind of judgement and is cruel isn't someone worth knowing anyway. life is too short, why fill it with hatred.
So yes, I understand being scared of your friends and families reaction, but if you do lose friends, which is very unlikely anyway i'd imagine, were they really friends anyway if they reject you? who you are as a person, who you fancy/love? why should that matter so much to them?
When I came out it was the 1990s, I was a teenager and I lived near Stoke on Trent. I was asked to leave pubs, leave bars and venues because I held hands with my girlfriend. I had people scream insults at me in the street. I was spat at when i was with a group of gay friends. someone tried to set my friend's hair on fire. Times have changed now, there isn't so much of this obvious and blatant homophobia. it's kind of more insidious now in a way. it's definitely still there, but it's less. that's why i hate it when people are like... oh why would you have any difficulty telling your friends and family? it IS difficult! depending on your situation. but it's very worthwhile.
For what it's worth, if you really like this woman, i think being open with your friends and family is worth a go.