He literally cut me out, overnight.
i suspect that for HIM it was NOT an overnight decision. that instead the wheels had been turning for some time.
he may have admitted to an affair in late 2017......but it's likely it went on longer than that. or with more than a single partner. usually when an addict "admits" to something, they are only revealing enough to minimize the reality.
then upon his revelation and apparent remorse, he sticks around about 3 weeks and then boom, he's got an apartment and a moving truck. and surprise, there IS another woman! and off he goes......
i think i'd be speaking with a lawyer ASAP, so that i have the power of knowledge and information on my side, so that i don't get further blindsided. you have a home and children to protect from his whims and deceit. i'd put nothing passed him. his actions clearly demonstrate his priorities.