Monster in law or Mother in law? ??

Ok I need opinions. I have 2 step children and a son of our own with my fiance. His mom has an xanax problem. She goes on binges when she gets her prescription and she takes up to 12 to 15 a day. She gets 60 a month and their gone in less than a week. When she is on them (during this 4 to 5 day period) she walks around like a zombie, hair greasy and going every different way, no shower, same clothes on, food stains around her mouth and all on her shirt. And recently smelling like urine and shit. She steals from me and my son, can't remember anything and has no perception of time or days.

When she runs out she goes through about 2 or 3 days of sobering up, blaming, then shaming herself. She apologizes, manipulates sympathy into all our hearts and then we let her back in and she's great the rest of the month. (Without her xanax prescription.) Lies to us saying she learned her lesson, don't even want a xanax, yadda...yaddda...fucking yada...

But while she is sober I feel like she competes with me on cooking, house keeping and bonding with the kids.

Here are a few of many examples.

She was in rehab the week before Thanksgiving. I decided in October to cook my first Thanksgiving meal all by myself. I did, I put a lot of research, and heart into this meal and it was amazing. The day before Thanksgiving she calls and says she is being kicked out because her Medicaid is not going to cover her stay there any more. None of us believe her and refuse to go pick her up so she calls her brother (who has an addiction he hides from his wife) to pick her up and bring her back to our town. He does. So we tell her she needs to get a motel for the night then we would go get her the next morning. (I didn't want her to ruin my first meal and she would)

So she comes over the next day and eats my meal and I cooked and complimented me on it. So I tell her for Christmas I'm just going to do a ham, greens and corn bread. We'll about a week and half into being back there she goes to the grocery store and buys A HAM, GREENS....AND CORN BREAD and cooks it. Exactly what I say I'm going to cook (in 3 weeks). I feel like that was her showing me this was still her house, her family, I'm an intruder. (Even though her and my finances dad has been divorced 10 years and she up and left every trying so she could sleep around and take her pills without her family seeing her, and she keeps coming back here. Not in a romantic relationship with his father but friend only) She wanted to out do me on a meal.

Here's the kids competition. My step son has aspergers so it took him a while to open up to me and we're still bonding. So me and him are having a conversation and she is so desperate to jump in it she comes and stands in from of us while we're on the couch asking questions. It's about video games, she has no idea what an Xbox is except she assumes is shaped like a box lol. Even my step son is looking her in annoyance because she won't shut up and she's all in our shit.

So that didn't work so she goea to my step daughter to try it. She's calling her princess and beautiful and stroking her hair a LOOKING AT ME WHILE she's doing this.

Rewind a little bit...before they came over that day I went and bought a toy for my step daughter because they got a knife for my step son for Scouts and I'm not going to let one child get a gift and not the other. This ate my MIL alive. So they go to the store and she buys a ton of candy and gives it to them and let my step daughter eat it damn breakfast the next morning when she had a fucking sausage biscuit on the table waiting for her. That was her trying out do me, to get back on the favorite side of my step daughter.

I may be wrong but my fiance agrees with me on this that he sees how she is competing. We'll my MIL got high last week (yes, after less than a month of being out of rehab )and my father in law took her to some friends house for her to live with. She is sobered up, and apologizing and begging to come back so my fiance told her his father every thing that bothers me about her when she is there. (Which I didn't want to happen) but it did and he totally defended her and me ans him.got into it because no matter how much I explain he can't grasp what is im saying. I can't expect him to anyways since he has fallen for her tricks over and over and over again.

I had to vent. Wheewwwwwwww.....

So is she monster or what??