Also my mum wouldn't care if I said that to her if she was here she would just laugh and say she never wanted any so it wouldn't bother her.
This is the sad and painful reality for you, isn't it @Ilovechinese. it's the grinding realisation that your mum wasn't who you wanted her to be. Hence it probably didn't actually need your brother to coerce her into anything. She didn't care that much, so to your admission, she wasn't of the mindset to bother about fairness between her childen, which would ordinarily feature in a fully-functioning loving mother/child relationship (as you have stated).
I wish it was possible to offer any sort of resolution for you. Whatever the eventual outcome, none of this will heal the gaping wound of your mother not caring about you the way you wished she would. No money will neutralise that hurt.
It's all too easy for people to glibly say don't let it consume you, walk away etc etc. Easier said than done.
It would be worth considering seeking professional counselling support - you are in an emotionally fragile state and are currently living off the adrenaline to survive the forthcoming legal action, if you choose to take it. When that's over, you'll come down to earth with a crash. You need someone there to catch you, so it would be advisable to seek the support in advance to give you strength to carry on, whatever the outcome. You could start with your GP and see what they advise.