Quick answer
You may need arrangements for children, housing, bills, and support before deciding whether to file for divorce.
Do now
List immediate needs and existing orders. Make a private inventory of household income, recurring bills, and documents you lawfully possess. Record a proposed temporary schedule and who will pay which bills. Seek legal review before signing a separation agreement or moving shared assets.
Watch for
Moving out, changing locks, or relocating children can have consequences. If there is abuse, use the safety section first. Local family-court routes are described above; legal separation is not the same as divorce.
Official sources
NJ Courts — Initial FD application packet, NY Courts — Starting a Case in Family Court, DC Courts — Family Court Self-Help Center.