My world has come crashing down when i found 100's of child porn images on my husband's laptop. We have a beautiful family. What should i do?

Not to defend him, but would like to offer another take on this. Being sexually stimulated by these images may not necessarily mean that he is actively acting out these fantasies. Some people get aroused by such images and only looked at such materials in private. Though I would agree that the risk is still there that this will escalate into actual behaviour (if it has not happened). I suggest having a talk with him. May also be good to have a chat with your children (really sorry to suggest this but it would be good to ensure that your children had been safe from any potential abuse) to check if any inappropriate behaviour had been carried out. There are therapies available and it would be best if your husband is keen to seek professional help. Think through what is best for you and your family and take care! I hope you can get through this difficult period.