You have not made a horrible mess of things.
You've had a crap start in life.
You really have. I can't even begin to imagine what it's been like for you.
My heart breaks knowing what you've had to put up with from your parents.
What did shelter say to you?
They may have a better way of getting you some accommodation.
Make sure you tell them absolutely everything about your current living situation.
Alcoholic, aggressive father, the whole lot.
Is there an Al-Anon near you?
They can really help with supporting you with your alcoholic dad.
They are there for people that need some support and it may be a really good thing for you to do.
You say our dad 'threatened' to hit you.
Has he threatened this before?
Has he been physically abusive to you in the past?
I'm so sorry you lost your mum.
You don't have to tell the father unless you plan on keeping the baby.
The fact you pestered him for a drink, does not make him, breaking his vows and cheating on his wife, YOUR fault. It really doesn't!
So don't go down that thought process at all.
Is there a Marie Stopes centre near you?
Have a google.
They can help you with the decision on what your options are with regards the pregnancy.
If you really don't think you can continue (and that is totally your decision and nothing wrong with it) then the sooner you can get things sorted out the better.
I really want to reach the screen and give you a big fat (((((((HUG)))))))