I’m sorry you are feeling the way you do. Try and remember this feeling is not forever. You have a lot on with 3 kids, which I presume are quite young! You are right, they do need their mum, so it’s important that you take this seriously. You can’t give up.
There are 4 main ways that people stay well when under pressure, pick one to use, it will make a difference:
Social Support
None of us make it through this world alone, we all need others. You say you have no one and this won’t be helping. Where are your school friends? Neighbours? Any ‘mum’ friends? Is there one thing you can do to reconnect with one person? You don’t have to offload to this person, just being with someone can help
Finding some purposefulness
Being a mum is great for purpose but for many it all consumes us and we end up losing our ‘other’ identity. What do you have outside of your dc to give you meaning? Do you paint? Sew? Write? Run? Walk? What is it that you are not doing that gave you pleasure? How could you fit this in your life?
Your thinking
This is where things like CBT / therapy may help. You are probably catastrophising your situation...so if one thing goes wrong you think EVERYTHING in your life is bad...it’s not, there will be good amongst the shit if you pay attention to it, the sunshine today for example. You are probably thinking life is ALWAYS going to be like this, it’s not. This is temporary, a blip and you (like many others before you) will make it through. You probably also think it’s just YOU that these things happen to, they don’t, it’s nothing about you in particular, life is just tough sometimes. It’s nothing you have done.
Therapy /cbt can help you get rid of these harmful thoughts. Have you put yourself on the waiting list?
Confidence is the last thing people do to get through tough times. It is right at this point you are at now where you need to play back the things you are good at and use those skills. What have you succeeded at it your life? (If you say nothing - see above about your thinking) how are those skills useful, today?
If you don’t know, you really need to know. This can be a task, finding out your strengths, there is something there I promise...you’ve just got to find them
Life is really tough, at some points seems unbearable, but you can do this. It honestly truly won’t last forever, you can feel ok.