Hi BRM05, you're going through an awful period right now, and it's must be terrible seeing the children in pain. One of the worst aspects of living with and loving an A is the realisation that you can't control them. You can't keep them sober and you can't force them to stay married to you. The more you push, the harder she will push back.
Your post implies she might be drinking again as she's working in place that serves alcohol. Do you have any more indications, like when she talks to you?
I suggest you take things softly and slowly but make your plans. Nothing has to happen tomorrow, but you can't hold back time either. Get legal advice, especially around custody, because you can't trust her alone with the children until she has some solid sober time together.
Currently she's in the exciting stage of a relationship, coping with sobriety (I hope) and is completely wrapped up in herself. Stay calm, don't fight her unless you have to, and if she's still intent on divorce don't go down the adultery route. Neither your or the children will benefit from that.
You will benefit from planning for the worst even if it doesn't eventuate.