I spent yesterday evening telling DP that I think his children are rude, lazy, arrogant, entitled, badly mannered, bullying and selfish individuals. I told him that they are the product of the petty arguing between him and his ex and that his whines of "I just want to see my kids" are pathetic and he should want his kids to grow up to be decent people instead of only thinking of his own needs. His ex wife is nasty, arrogant and controlling and he has an uphill struggle to teach his kids the right path, but if he makes no effort, they are just the product of her teachings, and boy does it show!
This all came about after his eldest spoke to me like a piece of dirt for the last time and DP just stood by and let her in front of an outsider too (the look of shock on her face was a picture!). It's been building up for some time. His eldest is constantly looking down her nose, ignores at best and at worst critisises and judges me very vocally. Snide put downs are about the only time she talks to me or my son, her siblings or Father, the best you can hope for is for her to talk about how wonderful she is.
I won't go into the details of how they behave, I've documented it well here in the past, although it's tempting to have a rant.
DP took everything I said and didn't defend his kids once. He said he hasn't always noticed things but said he did want his kids to be "nice" people and behave properly in public. I was waiting for him to start critisising my son, but he didn't. He said he will have a "word" with his kids at the weekend. I told him it will take a lot more than a "word" to change things.
I've told him I will no longer work to keep the peace for his and his kids sake, I will defend myself and my son every time we are disrespected and he should expect a lot of resistance from his kids and ex wife. I suspect it will push them completely away from me and against my son. If DP does back me up properly, then I suspect there is a good chance he will lose his children.
I've also told him that I am not prepared to live in a battleground in my own home and at nearly 40 years old this is not my problem to have to live with.
So, if I stay angry, I can use it to assert myself more and keep on reminding myself that I have a right to be spoken to with respect in my own home, that I have a right to my own possessions and space. I have the right to bring up my own son in the correct manner and teach him not to tolerate bad behaviour, abuse and bullying.
However, no-one stays angry forever and I know it's not healthy anyway. I am by nature, not a fighter and an arguer. I learnt from a young age to smooth things over and keep the peace but I know that attitude is not the right way forward in this situation. It's what has brought me to this position and done me no good whatsoever, except that it has given me time to learn a lot of things!
We are still on the waiting list for Relate. Have been waiting 6 months now. We got an appointment but DP answered the phone and said he would talk to me and let them know if we still needed it. By the time he told me and I phoned back, the space had gone, so we've been on the waiting list for months! 
The way I feel now, I don't want to talk to anyone about it and to try and be understanding. I think everyone else has had quite enough understanding from me and it's about time I started being caring to myself and in turn, my son. I don't discuss too much with my son, but he put his arms round me yesterday and told me to "not let the DSC upset me and to think of nice things". 
So to those of you who have been kind enough to stick with me and my rants on here, I ask you, how to keep this momentum? To be so damn determined to not put up with this anymore. I was thinking of giving myself a time limit to live with things before I give notice to the tenants living in my house or decide to stick with it. I've sorted out a lot of the practical things that needed sorting before Xmas when I was last properly considering my options, although of course, it's a daunting prospect arranging to move furniture etc. with DP being resistant.