MIL - Help pls ...

I've posted about this before .. re posting my previous post in a screenshot below . I'm having issues with her again . This is going to be a long rant so excuse me and thank you to the ladies who've taken their time to read through this all and give me their honest opinion.. I'm 22 Y/o - My boyfriend is 32. We live with his mother in a shitty apartment because they make minimum wage salary. (i make 3x both of their salaries and they know it ) I've encouraged my hubby to go to school and have even offered to pay for his courses. I don't mind and never will, he treats me like a queen and it's the least I can do. His mom on the other hand has been a pain in my ass since I moved in with her petty behaviour.. Today I asked her out on a dinner date with my boyfriend for this upcoming Wednesday in which she responds with "Who's paying? (insert hubbys name ) never has any money because he always wastes it . -Snickers-" in which I replied that he got his tax return back and even then we wanted to treat her so it shouldn't matter.. she kept going on saying that he doesn't ever have money because he doesn't make a good wage (neither does she - they make the same soooo...ok) then she started saying that I don't really know him and hes been the same since he was 16 and he'll never change .. again I chimed in and brought up how I was and am more than willing to pay for his college so he can achieve a proper education.. She just scoffed it off and said that he'd never accept my money because he could never pay me back .. which is so not true .. why wouldn't she be happy that his long term significant other is willing to help support her own son? ugh. The previous week there was a get together with my SIL and she didnt even invite me but she got on my hubbys case for not being there and having to work. it's seriously depressing me I'm trying so hard to have a relationship with her but she's such a bitch and I don't know why. I've told hubby about all of this and he's not happy with her.. he plans on talking to her but i just have a feeling that's going to make things worse..