I never thought being a step mom would leave me feeling sad, lonely, angry, frustrated, and depressed!

2 years ago, I left a lucrative career as a professional to move my 2 biodaughters (now 6 and to be with my BF and his 2 kids (now 14 yo son and 13 yo daughter, has them every other week) to a small town. I gave up my home, my thriving social life and my freedom to be with this man who I thought would be an incredible role model and support for me and my daughters after being with my ex who was an abusive alcoholic.
Although my BF is an incredible human being, I was not in love with him and I was not ready to be in another relationship, but I moved in with him anyway for reasons that I do not need to share at this time. During the course of the relationship however, I have grown to love him and we now have a beautiful little daughter together.
Our large blended family generally works well. There have been some issues with SS as he has expressed his desire for his BM and his dad to get back together. During our first Xmas together, SS asked my BF to spend XMas at BM's place (sleep over on Xmas eve) so they could all be together as a family to open presents. Or failing that, for her to spend Xmas at BF's house. My BF actually considered the latter and tried to convince me that she had a right to be with 'her' family. I was not so much upset over this idea, as I was at BF for putting me in the place to make the decision. Of course I said no, that I wanted to create new memories for our first family Xmas together, she gave up her 'family' when she initiated the divorce. I was incensed at BF as I thought he should have instictively known to not even consider this idea let alone be so thoughtless at pulling me in and then using me as the bad guy.
And the emerging trend I've noticed is that BF puts me in a place where I am the 'bad guy', because I don't think he has what it takes to be a more forceful parent. He parents with an attitude that he can deal with his kids in a respectful manner so as to allow them to draw their own conclusions and make their own decisions. When a problem arises involving the skids, he takes them aside, in a private area away from me, and calmly explains the situation – there is no show of anger on his part and there are no consequences, not even an apology or insisting that the problem be resolved by the person who caused it. I find this to be very ineffective because not only am I excluded in the parenting, but I am not given an opportunity to voice my thoughts on the situation (which often has something to do with me or my kids). Not to mention, this parenting style gives the skids the ability to control and manipulate any given situation, which they do, and it is tearing our family apart and destroying my relationship with my skids and BF.
The latest incident – and one that keeps popping up – is sharing the couches in the family room. My SS insists on taking over 1 couch since he likes to lie down while watching TV and my SD does the same on the other (we only have the 2 couches). The other night, my biodaughters wanted to sit and watch tv – SS would not allow them on his couch, while SD only allowed enough space for 1 daughter to sit on the edge of the couch while my other daughter could sit behind her on the head rest of the couch. After over-hearing the conversation that went on between them, I spoke to my BF about this incident, he approached his kids in his normal parenting style. He then reported back to me with the story he was given and that's when I knew definitively, that his kids were capable of lying (I always gave them benefit of the doubt). And in his typical style, he believed his kids over me, or at least, made me feel like he believed his kids over me. It is quite obvious to me that the skids are lying manipulators and because my BF insists on parenting in the manner he does, he perpetuates the behaviour. Had he appproached his kids in front of me, I doubt they would be so quick to lie directly to my face because I would have called them on it and chewed them out for it. I do not parent in the same manner as my BF and I do not tolerate any kind of manipulative lying behaviour in my biodaughters – and they try! - and I certainly do not tolerate it with his.
So, this last incident has really done a number on me and my relationship with my BF and skids. And once again, I am not so much angry at the skids (though my opinion of them is quickly changing from good to bad) but at BF for having allowed this to snowball out of control and for not getting the behaviour under control the first time it happened.
I only wanted to be with my BF and to raise our children in a family that we all deserved to have – it was our second chance to do it right! But our differences in parenting have left me defeated, angry and incredibly depressed! I feel incredibly alone because not only can I not turn to my BF for his help, but he has made me feel like I have a vindictive skid hating agenda when in reality, I just want to have a normal functioning family where the parents are the rulers/leaders and there is fairness amongst all children. If I had of known that this was going to be my life, I would have ran as fast as I could have in the opposite direction. While I am the kind of person who quickly forgives and forgets, and who presses on with a positive attitude, it is becoming more and more challenging to take this approach. I've invested so so much into this family and have gotten so little return on my investment. Getting out of the relationship is very attractive to me, but I do not have a job, my daughters are settled into the community, and I hate the thought of raising our shared daughter in separate homes. At the same time, I cannot live in house with so much tension and negativity and continue slaving away for skids towards whom I have a growing hostilty and a BF that accuses me for the problems we have.