Hey Arthur,
I guess mothers day is coming up real quick; but I'd like to offer a suggestion. It was something which as a kid I made at school for mothers day. Our schools usually set apart time to allow kids to create something for mothers day or fathers day; and that year a project was to create a jar filled with compliments, or appreciative statements about our mothers.
I made one for my mother, put pretty ribbon around the top; she never opened it. It sat there; and sometimes I'd ask her if she's going to open it...but she'd just deflect it.
I think she threw it out.
In therapy years later, recently, I decided to make one for another family member who I thought would appreciate it more; I got a wooden box painted it all white. Then started painting black zebra stripes on it.
Our house has a lot of animal themes, and I like zebra; so I figured it'd fit right in. But I never finished this box either, because amazing my family decides to kick me out; and I stopped going to therapy after that.
Though I am not kicked out; I just stopped going. I got disheartened. It's also ironic that I was making this for a family member who in turn decides to back stab me, and basically wants to see me homeless. They still mock me with homeless statements.
In any case; I haven't been able to successfully give something like that to someone; however the idea is very powerful, because it would show your mother the things that you appreciate about her, and what she does, who she is etc... that you probably never say.
It would show her that you do notice the good, that you do love her, and that though you can't always show that; at least she can always go back and look at this gift and be reminded that somewhere inside, you appreciate and love her.
So that is my suggestion to you, if you want to make it; you can use any sort of container. You can get a jar, or a wooden craft box. Or you can purchase some nice kind of jar or box that's already made.
What you do next is cut out strips of paper (depending on how long each statement is going to be); or write notes on pieces of paper and fold the notes so they fit; and then place those in the item you chose or made.
You said you really need to get her something good; I think this, could really be good to her; could show her a side that she's been missing for a long time: your compassionate, caring, appreciative, loving side....
I hope you can find a good gift that is suitable this mothers day.
P.S. I understand what it's like to lash out, or have the exact opposite reaction as to what we are really thinking or feel about others, toward them. Like how you said you threatened your mom, whereas in reality you probably adore her a lot, and need her on many levels.