What a hard a difficult decision to be faced with so early in recovery. I don't know where you live or what things you might enjoy doing but here are a few that may interest/be available to you: cinema, evening classes, walking (dogs if you can borrow one), jogging (see if there is a local group that meet in your area), get creative, or go Geocaching. (Lifesaver any time, any place & completely free)
Have you tried joined an online depression forum? I found it helped me at times, as does SR and other online help forums ( though triggers are rife on certain sites!)
Check out other avenues like local mental health charities, joining a 'tidy up' group, volunteering etc...
I would not attend a party on my birthday where there will be alcohol involved.
I have no advice regarding what you should/shouldn't do other than to make your sobriety the single most important thing in your life above ANYTHING else.
Without my sobriety I may not have another birthday to look forward to & my sobriety date is now the more important, to me, of the two.
Birthday: 38 years old next
Soberday: 06/10/13
Almost a year in & looking forward to the next and the next and the next and forever, one day at a time
Congratulations and welcome x
Driving my wagon of hope through beautiful views on my road to myself