That's atrocious, nobody should be that harsh to another human being! I'm sorry that these people have been so rude when expressing their frustration at your situation - even if that is the way they feel they should never put it as bluntly as that
It's hard when you are so consumed by dark thoughts that this is all you can express, I know the feeling and received pretty much the same treatment myself. In fact, because people spoke to me like that, I even passed it onto someone else, someone very close and vulnerable, years ago; it obviously devastated them and I've never forgiven myself for it since (luckily they did!). I thought that how how people were supposed to deal with it, being as people didn't hold back from saying that stuff to me - I was wrong and they were wrong.
You need better people around you to talk about this stuff to - are you close with anyone here? Forging a connection where you can speak about these things without judgement is priceless in this situation and key to your survival. From there you can let it all out in a safe environment and work from more solid ground than that which shifts under your feet with dodgy connections.
Having been on both sides of this, I am firmly on yours - it's truly disgusting for a mother to tell her child to "just overdose already", she needs a slap and to remember what her responsibility is to you as a parent.
The fact that you don't actually want to do the deed speaks volumes and what you really need is proper support; therapy and friends! Do you go to therapy already or have you considered setting some up? Are there any other members of family who are nicer and more supportive?
I feel for you and am sorry for the treatment you have received. If you need a friend, or even just a sounding board where you are not judged and dismissed, my inbox is always open!
PS what they are saying is down to their own frustration and impatience, not down to you. There are better ways to handle this and unkindness isn't the answer x