If it helps you are not alone in this, and you are not really going insane, it just feels like it. I too have a step daughter who is 30 and is the nastiest meanest rudest person I have come across in my life. She is far from attractive inside or out but she thinks she is the most beautiful woman on the face of the earth, she honestly believes that everything that comes out of her mouth is right, and constantly belittles people. Her treatment towards me was appalling, and after 8 years of it, I banned her from my home. That will be a year next month. However, what I came to realise was, that she was not my problem, she never was, the problem was her father, my husband, who did as your is doing, nothing. My husband actually told me in one of our many arguements about her that all of the trouble we were having was my fault not hers, if I just shut up and put up with her crap then there would not be any problems. I could not believe it, he actually wanted me to just take it, and he meant it. He too wanted me to be her doormat, wanted me to take her disrespect, her hatred. She made it clear to everyone she wants both her father and I dead and she will take our house, can you believe it, and her daddy's response she is just upset, she doesn't mean it. Well she does mean it. But her daddy will never, never tell her to pull her head in.

Unfortunately I think you will really have to make a decision yourself as to how much of this you are prepared to put up with. By the time I banned this woman from my home I was prepared for my husband to leave, actually part of me wanted him to leave because I see him as the problem he is the one who allowed it, who by his silence condoned and encouraged it.

Your husband and his daughter are set in their ways and are unlikely to change. It is unfortunately all up to you to set the wheels of change in motion if that is what you want. It took a lot for me to reach the point I did, however I was so physically and emotionally ill from the years of abuse from her, and from DH allowing her and supporting her in this that I saw no other option. It was stop all of this or have a nervous breakdown. I chose to end it. I am so glad I did. Putting up with it caused me to lose my self esteem and my confidence, getting rid of her has helped me to find myself again. I would not put up with this kind of behaviour ever again. It is soul destroying.

I just wanted to offer you some sympathy and commiseration. If you've gone a lifetime basically getting along with everyone in your life, it's quite jarring to have someone enter your world and not be able to get along with them.

I would be upset too if someone did all those things to me. You are not insane at all. I would not allow a known drug user in my home ever and I think you should not ask your children to be around this woman.

I'm sorry your fiance is acting like this. Have you considered separate living spaces and perhaps forgoing marriage while remaining in a relationship? He obviously has other qualities that you value.

Good luck to you, dear.

I agree with Stepmisery. Put the marriage off until some strong boundaries are put in place. She should not be allowed in the home if she is stealing / taking things without permission. If she does have something in her possession as she is leaving call her on it. Say , please leave that item here it is for ALL the grandkids not for you to remove from our home. Too bad if she gets embarrassed - she will soon learn not to take things without permission. Your DH indulges her and he needs to stop and enforce some boundaries with her. I know just how you feel, as one of my SD's feels entitled to stuff in our home too and will not hesitate to ask if she can have "it". I say no, but later she will ask DH when I am not around and he gives it to her. Grrrrr. Jerks.

Yes it is your place to put her in her place. This person has stolen from you. If an adult did this to me they would never be allowed in my home again and they would also be reported to police. Don't worry about hubs being mad. YOU should be mad. Explain to him that taking kids' stuff intended for all the gkids impacts not only on you and him but also all his other children (and yours of course). By behaving like this she will stop his home being a focal point for the family to gather because the other parents will not want to come by and have their children corrupted. That in itself is appalling and should be a wakeup call to him. If he wants her in the house then he must supervise her every move. Period.
You don't say what your living arrangements are but if I did not get him to agree with the above personally I would live separately.
Disgraceful. As so often on this site, drugs appear to be at the root of the problem. He has got to get to grips with this issue. People who do illegal drugs usually have to steal and lie to support their lifestyle. The lying is also brought on by the drugs themselves. It's never going to be better for him if he does not get this basic issue.

Unless your fiance agrees to change the locks and not allow her a key or access to the home you need to move. Your property is not all that is at stake. She can pass on a house key to some very bad people as her judgement is clearly clouded.

I know we think it'll never happen to us but I'm afraid it can.

I honestly believe that in step situations it is the biological parent's responsibility to discipline their own children. I believe that when a step parent steps into the role of "parent' and disciplinarian trouble always follows...............HOWEVER, my strong belief in that, led me to put up with crap for 8 years. So saffron5567 I think your therapist is right. If we have been abused and disrespected by stepchildren/step adults, we have told our partner, that's not on, and our partner fails a second time to deal with it, then we should not take it a third time. Honestly the truth is that the first time our dh/so allows this to happen is a loud and clear indication he/she will always allow it to happen.

My advice...run for the hills !!!

Sorry that this is happening to you. You are not crazy, they are. Stepdaughters are probably the most vicious. Read up on RA (relational agression), PAS (parental alienation syndrome) and narcissists/borderline personality disorders. It will help you understand what is going on. Most normal people are at a huge disadvantage when they have to interact with these borderline people. Add drug/alcohol addictions and it is crazyville. Learn about detachment. You need to detach from them in every possible way-the sooner the better because it probably will get worse if you marry or stay together. If they are stealing from you and disrespecting you in your home, and your man isn't doing anything about it or making you feel like you need to take it-then you need to get out (or get him out) and find a mentally healthy man who respects you. These are poorly parented borderline personality type adult addicts who feel entitled to steal and abuse people. They aren't going to change. And why should they? Their father seems to be allowing this, that makes him a problem/enabler too.

Knowing what I know now, my advice is to bail out. His kids, his problems. Don't let yourself get sucked into the drama. Don't invest anymore of your precious time and heart-they'll hurt you as much as they can. Run, don't walk away. Have your own home, a peaceful, sane home where thieves and abusers aren't allowed. No real man would allow this behavior, let alone expect you to suffer it in silence. That speaks volumes about his attitude and what you can expect from the whole bunch of them in the future. Good luck.