I'm sorry, but need to rant. I have posted a few times so you may have read my other experiences.

There are very few places for me to go when SS starts playing up and OH does nothing, so I normally take our 10 month old daughter and go to my room. It's very peaceful up there, my sanctuary.

SS and OH haven't been doing so well lately, so I've taken an extended break at my mums, to give them bonding time without me and DD around. On the way to my mothers, we discussed certain rules which needed sticking to. The basic good behaviour rules, for obvious reasons. No sleeping in my room or our daughters room. They are off limits.
Just to explain, we only have 3 bedrooms and my BS has moved in with us. SS7 was stopped from sleeping over so there was no need to keep our DD sleeping in our room, so we turned the spare room into a nursery.

Because I'm away, SS has been allowed to sleep over by BM (long story) but he would have to sleep on the couch. Not my problem as OH allowed her to stop overnight visits.

Well, first night he has him, OH decides to invite his mate over who is going to sleep on the couch, puts SS immediately in my bed.

There are so many things wrong with this, the major one being that OH didn't even have the decency to ask me if it was ok. He normally texts every night to say goodnight to us both, nothing at all tonight and then my BD18, who went over for dinner, told me that SS is sleeping in my bed.

Am I right to be really angry about this? The one space in the house where SS can't take over and the OH has handed it to him on a plate whilst I'm not there. The other problem is that SS soils himself every day. We've put him to bed in a onesie, clean after a bath (in the past when he was allowed over), and he's woken up with it up his back and down his legs! He's also been caught at aged 6, Googling for pictures of his dad naked. He's obsessed with his dads naked form and has called him sexy previously (I found this very disturbing but apparently BM uses the word sexy to describe many things and I was being OTT about it). I really don't think that a child who is obsessed with his fathers naked form, should be sleeping in the same bed as him!

If the father can't keep the rules, how can I expect his son to do so?

I'm already upset because OH's mother has virtually disowned our daughter, won't pick her up, take any notice of her, kiss her goodbye, anything - but SS is treated like the princess he is.
She sent my OH £300 to make sure he had a good day out with him, but sends nothing for our daughter.

I have now got to the point where I am refusing to have his mother around our daughter, am very close to telling him that his son is not welcome in my home either. He either has him elsewhere or we split up.

We are going to get counselling when I get back, but at this rate there won't be anything to go back to...