Swannest I am so sorry you are going through this.
You have lived unhappily for long enough. You have tried everything, so it really is time to start I totally different tack.
The thing is, even if your H had not torpedoed your marriage, it would have been a good thing to develop a more independent life alongside your marriage. Friends, interests etc. It strengthens your confidence and spirit, IME.
Start now. You are working, so build social networks there. Join anything that interests you a bit: a local Facebook Yarn Bombing group, any kind of volunteering, a class, a walking group, anything!
Look up old friends and e mail them or write to them.
As soon as poss book a trip to Aus without your H to visit your children.
Plan a holiday for next summer: something like the residential Skyros Centre holidays which feature different courses for solo travellers in Greece or the Isle of Wight, if you can afford it.
I live alone now for various reasons, and while sometimes I think ‘oh...it’s just me, no one to say hello to’ I treat the whole thing like a retreat and opportunity. My home, my space, my time.
I am going to have to make an effort to invite people round now we are allowed, but it will be worth it.
Living alone is FREEDOM.
And relieving yourself of the daily tongue biting and teeth gritting, managing your emotions in every interaction with your H will be such a relief.
The pressure and emotional load of all that actually drains your sense of self and undermines your confidence. You may well feel so much more confident and positive with him out if your life.