Dear MissHL I am so sorry to read your message. Last year this happened to myself and my partner although the AO had already gone through.
You've been given some great advice particularly from Italiangreyhound's post on Thurs at 02.32 who's advice I would echo.
Some things I did that helped me:
Reach out to those very close to me.
Sought individual therapy to support myself during this difficult time which really helped. Do look for a counsellor/therapist who understands the adoption process.
Couples counselling - after a period of individual therapy so my mind was clear about my wants and needs.
Giving myself as much self care as possible for me it was exercising, taking the dog out by myself and with LO so that my partner and I had some breathing space. My partner ended up going away for a few days each week (perhaps not possible for you at present).
Discussing with partner what their ideal future looks like.
We allowed the adoption order to go through and then started the process of divorce.
Our main focus was on LO's happiness so we tried to be as amicable as possible when living together.
More self care.
Lots more support from very close friends and family.
I still have individual therapy to support me during the divorce.
Look after yourself. These are such difficult times that we live in. 💐