My top advice for women going through it at any stage of the old old story that plays out here so often:
1 No, you're not going mad.
2 If it walks like a duck and talks like a duck - it's a duck.
3 If his behaviour, dress, interests, appearance, conversation, habits, smell etc have suddenly changed - something is up.
4 If he has mentionitis - something is up.
5 If his stories don't make sense - something is up.
6 It wasn't your fault. 'If you hadn't (insert bullshit) I'd never have (insert more bullshit)...' Is just that. Bullshit. He chose to do it.
7 Keep records. Receipts, notes, journals, screenshots, copies.
8 Get professional advice - solicitor, financial advisor, Women's Aid. Don't believe what he may try to persuade you to believe about your rights, the finances, the property, the children. He is not your friend.
9 Have a life of your own outside the relationship, the family, the home - your network; old friends, relations, colleagues, interests, plus income and pension.
10 Always have a plan B.
What would you add?