Looking back, there were red flags, but I didn’t see them clearly until I was deep in the relationship. The love-bombing, the gaslighting, the sudden coldness. What were the signs that helped you connect the dots?

I didn't know what a narcissist was until recently. Started watching videos and reading articles about it. I'm now able to identify my sister and her daughter as such based on the way they treat me. Everything that @Shadow has mentioned about. Gaslighting, love bombing, etc. 

When he kept insisting the sun reloves around the earth and I stated to even doubt what I learned in grade 1 science...

Red flags but didn't see them at first, stumbled upon a website listing all the signs and he had every box checked off....

My sister is a narcissist too. she constantly wants praise and never ever thinks she is in the wrong. I cut ties with her. she loved to be a control freak too.