You can file for divorce. If both parties can agree on each and every term of their divorce, including asset and property division, debt division, child custody and issues of support, the parties may file an uncontested separation agreement with the court.
Please do not hesitate to contact my office if you would like to schedule an appointment. My Firm charges a simple flat fee for uncontested divorces.
You can file for separation and continue to live together in the same house. However, a legal separation is not a step toward a divorce, but rather an alternative if your goal is not to get divorced. If you are planning on a divorce, it make more sense just to file for divorce now - and, yes, you may continue to live together while that is going on.