Hi OP
You have my sincere sympathy on the loss of your child.
I am so sorry for what you are going through; I know what it’s like because I supported someone through a very similar relationship - in fact, you could be describing the man involved.
You have been taken over by a man who has Narcissistic Personality Disorder.
These men are very, very clever at manipulation and making you doubt yourself because that’s how they like it -they need to be in control of you.
It can be very difficult to spot the behaviour too, because you’re a “normal” person I.e. you take most people at face value and don’t have an agenda yourself.
Narcissists are always wearing a “mask” and it is not often you will see the real person underneath; only when they feel they have enough control of you will they let the mask slip, in the knowledge that they can charm/gaslight/bully you into believing that what you saw of their real selves wasn’t what you saw.
Please, please, please get professional help. You need a psychologist who specialises in recovery from this type of relationship, who will unpick his behaviours with you until you understand the actual dynamics of the relationship and the loss of will/power that results from it. Your psychologist may well use EMDR as a tool.
You can find a registered psychologist via the BACP website.
I wish you all the very best.