I had to change a lot of my social life to stay clean, including bowing out of events and making up excuses as to why I couldn’t go. One of my dear friends who used to be a drinking buddy kept inviting me out, and eventually I had to confess to her that I’m in recovery.
I actually wrote about it in this thread, when I was about 3 weeks sober:
She was nothing but kind and understanding. Last week after 200 days sober, I was able to go see her at her new house. No parties, no drinking or drugs, just us hanging out and eating a good dinner.
The time will come when you will be able to go to social events again. That time is not here yet. Think of it like taking antibiotics for an infection. You have to finish the antibiotics even if you start feeling better. Otherwise the infection will come back stronger and harder to treat.
If this is your best friend, they will understand. Ask to skip out on the bbq and see if you can come over another time to give them the housewarming gift–with no alcohol involved. You don’t have to try to “prove” anything, you just have to stay sober, no matter what it takes.