Oh you poor love.
You will cry buckets, you will feel anger like you have never experienced, you will want to stay in bed all day with the duvet pulled over your head, you will feel all your emotions have overloaded and that you cannot take any more.
You need people around you that you can tell, you need to let all that weeping and wailing out (away from the children if you can), you will need this for quite some time. The pain is so palpable it feels like it is physical and you know what a broken heart feels like.
If you find it possible, hold onto the idea that it will pass, it will pass, the tears will reduce, the broken heart will mend, at your pace, then do. Because it will, it does. It really does. Although at the moment I cannot imagine that you can believe this. He has trashed your dreams, what you thought was real, your world.
And...
Each day try if you can do something that reminds you that you are whole without him. Even it if is just eating a morsel of food with the children and having a light conversation about their day.
Do something that distracts you. A warm bath, a peice of music, a painting, a walk, a ride on a horse/bike, a swim. You need to soothe yourself like a child does when distraught.
Call a friend, or your mum or your sister or your brother or the samaritans, pour it all out as many times as you need to. See your doctor if you have one that recognises that sometimes you need help to get through these hideous early days of recovery from betrayal and loss.
When you are ready to face practicalities, come back here, there is advice aplenty.
If you are not ready for practical advice yet then there are shoulders aplenty too. We have broad shoulders, and there are many of us and we can listen and we can weep with you.