Mila, This is early days in MLC terms. Sorry, but that is the case. His forgetfulness is part of his MLC. I truly thought my h had Alzheimer's for a few months near the beginning, the forgetfulness, erratic behaviour and personality change were so very marked.
In one sense he probably always was wearing a mask, but never doubt that he loved you [and almost certainly does, somewhere in there, and that frightens him too] but he is dealing now with stuff he tried to stuff down.
So yes, you will be alone, and it will be tough, and you will survive. It may also be fun, challenging, and you will move right out of your comfort zone. I would not have chosen this path, but I have learned a lot, and changed a lot.
It is very very tough for your daughter too, my youngest was 18 when all of this happened. They see us hurt, and their faith in their father is shattered, but they don't want it to be.
Think hard about another relationship. We are very critical of our husbands rushing off from us to someone else, but in reality a year and a half without affection, while it feels a long time, isn't a very long gap, after a marriage of over 30 years.
Are you so very sure that you are over your h? And thus ready to date. Many people start another relationship because they feel abandoned and rejected, and don't grieve fully and deeply for their spouse and their marriage. That puts a lot of strain on the new relationship