If you are absolutely sure that Divorce is the answer, then by all means file. As your lawyer pointed out, it takes a while for the paperwork to be processed, filed and signed. If you file, you can always pull the papers back. Also, the divorce decree is only a sheet of paper and if some time down the road after the divorce he wants to reconcile, there is nothing that says you can't...but remember...you will be the one to decide if you want to try to reconcile if that opportunity should arise.
Think about what you want to do and please to not allow others to make the decision for you. They are not walking in your shoes. If filing for a divorce feels like the right thing for you to do, then do it. If you have any doubt, then wait a month or so.
Keep the focus on you and your children and live your life to the fullest. If you opt to file, we'll be here to support you not matter what you decide to do.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.