Sorry you are going through this. It is horrible and just takes time.
I remember when it happened to me I physically couldn’t eat anything, couldn’t sleep, very tearful all the time and of course the tiredness makes that worse.
I think you have to find some good support networks. I was very lucky to have great friends for emotional and practical support and also my boss had been through a breakup a year or so before, and he was so supportive.
The other thing that helped me massively was exercise. Whilst you won’t feel like doing it, wrap up and get out for a walk, nature is so calming.
You will have good days and bad days. Sometimes it feels like one step forward and two back but then one day you will realise that actually the day has been good!
I read a lot of self-help books. I found comfort in knowing other people have been through similar experiences and could relate to their feelings. Try Paul McKenna how to mend a broken heart and Rosie Green has also written a book about her breakup experience.
I also had some counselling, which I found really helpful as I looked to my new unplanned future as it made it less scary.
it will get better.