Hi all. I'm in a bit of a hard place right now and was hoping for some words of comfort/advice/support/whatever.
I have 2 sons with my ex, they are 8 and 6. We split in 2009, after nearly 9 years together. 6 weeks later he introduced our children to his new girlfriend. The later moved in together and got engaged. Then early last, year they split, and he begged me to take him back, saying he'd made a mistake etc etc. stupidly I did, although not until August. We took things slowly, he didn't move in etc. then in may this year we decided to separate again. Despite the fact I loved him still, we realised we had changed too much now. For example, my plan was to go to college and then uni to become a Midwife, gee thought I should just 'get a job in Tesco' and didn't support me at all in following my dream.
Well 3 weeks ago he announced in Facebook (I know I know, I should block him etc but it's a good way to keep in touch if I run out of credit on my phone) that he's in a relationship. This is despite the fact that he spent the last couple of months trying to Getty another woman into bed, while messaging me telling me how he feels and that if I'd only change he'd have me back 
So the week after meeting this woman, he introduced the boys to her. Ds1 is not happy (think tears and tantrums after coming home and the next day, carrying round a photo of Daddy) because all they do now is spend time with her and her kids, and he wants to spend time with his Daddy. Ds1 phoned hood Dad to tell him this, and was told 'she is part of our family now, if you don't like it tough luck' 
ds1 then told his Dad that he's only going to go out with him sometimes because he doesn't want to always have to spend time with the others, he wants time on his own, to which he was told yea fine whatever.
To make it clear I don't want ex back at all, but how do I cope with the feelings of jealousy, more that he can move on and I can't. Not because I'm harbouring feelings for him, but because my childrens welfare comes first, and I wouldn't dream of introducing someone new to them for a good few months, plus I only have 1 day without then so of course even meeting someone new is impossible.
Plus the emotional strain of seeing my sons heartbreak every week ? 
Sorry it's so long, I didn't want to miss anything out, although I probably have
And thanks.