Hi Op. Firstly, you are doing an incredible, amazing job. You are completely capable of this (despite your challenges) and deserve your place there. Keep telling yourself that.
Secondly, Identify exactly what would help your condition in each of your classes and speak to your supervisor directly about that. And be direct. Map out the practical coping strategies that help to manage your condition and explain these fully to your supervisor. Then, if possible request a mtg with each of your tutors and ensure they understand too. Educating your tutors about your condition and requesting them to modify their methods should help you through the more complex and challenging aspects of your course.
In parallel, get a sit down with the pastoral care team at your uni. Talk things through with them - about your condition of course but really mostly about your family situation. You won't be the first or last person to break a family mould and head to uni with the weight of their issues on your shoulders.
Try not to catastrophise your future. You are not responsible for your family and you are not responsible for any failings there. It sounds like you may have been the solution to many of their problems in the past and now that you are no longer around for that - well - it's easier for them to disarm you of your self belief than to outwardly encourage you to succeed (they may feel it internally).
Also, and this may seem strange, but find a properly qualified sports psychologist. They are truly amazing at helping you realise your self worth / belief and how to apply that to many situations in life - not just sport. Try it - you'll be amazed.
Seek help now OP. Things will get much much better. Hang in there - your future self will thank you. 🙏