Here comes the rollercoaster...
Dear Once bitten, twice shy
Welcome to the forum. I am sorry you have had a such a devastating experience. I think you are saying your husband will be leaving again. This must be so hard. Then to find he is cheating must be a double blow. However strong you are it is still painful and something you do not want.
How are your children coping? Or do they not yet know about this second blow? They will of course need you and your strength to get through this horrible time. Have you asked for help from anyone? Posting in here can be helpful and I encourage you to do so. There are many here who have experienced the same or similar situation as you and will support you.
My husband and I separated nearly 20 years ago although this was my decision. It did not make it any easier. I fell into a huge depression and seriously considered returning but my common sense stopped me and I think this was the right decision. Not often I listen to my own words of wisdom but I did on that occasion and found it both an incentive to make a good life for myself and to remind myself that I could get through the hard bits of life.
Although you realise the road ahead will be a struggle you know you have gone through it before and can do so again. This is an important aspect to remember especially when on those very dark days. I found if I looked ahead only to the next day I could manage more easily. Sometimes it was only the next hour. Small steps mean a lot in recovery. I found these small successes gave me reassurance that I could survive and helped me to look forward.
The emotions we experience can be so hard to manage. Your description of them as a roller coaster ride is so right. This is exactly how it feels. Have you discussed this with your GP? It may help and perhaps a few chats with a psychologist. Your GP can arrange this. Having someone who is fully focussed on you is helpful. Most of all you can talk about managing that pesky roller coaster.
In the meantime, please continue to post in here. It can be helpful to 'vent'.