I havent voted as I wasnt sure what option to go for.
I have noticed the majority of girls (including me) dont seem to get a long with their other haves Mothers. Its a territory thing that we just cant seem to avoid.
I think me and my mil tolerate each other rather than get on.
I have learned it helps if I dont see her a lot
H and I have been together twelve years. First time I went to my H's house and met his Mother she said something like 'nice to meet you, please take take your shoes off before you come in to my house'!

I get that its her house so her rules but I felt that right away she laying down the law.
Me and my mil are very different in every way We only real have her son in common. I used to think H would always side with his mom but it was over the years ( a lot of them) I have learned to just let things go over my head and not put H in a position where he had to choose a side. I am also hoping H notices this and that I come out as the better person.
Its a shame that you were made feel that you had to apologize. Thats not going to make you feel better about anything. I think things will only get worse if you try to get an apology from her but I can totally understand why you would want one. Its hard to say forget and move on as you probably wont forget, if you're like me - things will just niggle at you for ages.
I try not to give my mil any excuse to get upset with me or to coz bother with me and H but its not always avoidable.
Sorry not much help but I dont sympathise with you.