Is there any other family members you can reach out to that might be able to help? Someone who understands your mother's short comings and would want to help you? If so, reach out.... they probably don't want to see you or the kids hurt either, and you do deserve a shot at the life you want.

If not, contacting police or childrens aid may unfortunately be the only choice if you're unable to keep them (which is understandable 100% given the circumstances and that you are not financially able to support all 5 of you while in university).

Lastly ... I'm sorry this has happened to you. It sounds like you have a big heart and have done your best. You deserved a better life and to be a teenager instead of raising your siblings. You're an amazing person for having done what you have already and I hope you never forget that.