😢 oh no, poor mummy... If you arent happy with him anymore, then divorce him and claim child support... I never believe in staying in a bad marriage for the children, especially if the other party does not care about the children in the first place... If he already treats you and your child poorly now, he will definitely treat you even worse in future. Who knows, maybe next time he might be the one initiating divorce when he manage to find your weakness and then take your child custody away... Then it's prolly worse for your child and you at that time...
Since he has cheated on you, as long as you have evidence, it is already grounds for divorce. Another supporting reason can be lack of quality time spent with kids... Remember to keep evidences of these. If anything happens, you will at least have an advantage over him for child custody...
For now, maybe look for some mummy groups on WhatsApp or telegram etc. Its good you made the first step here... Make some mummy friends in the chat, I'm sure the other mummies will help you whenever you have any problems and at least you got people to talk to. You might even make good friends with them and your toddler can be good friends with theirs as well. It will be better for your mental health if you have friends to talk to and help you... I feel sad about your situation, even your mum is not helping you. Maybe try communicating more with your mum and let her understand your situation?