Last night he said to me, calmly and thoughtfully -
"we're not a family so I don't think you should think of us as one. We're a couple, you have your kids, I have mine so we're a unit - but we're not a family and never will be."
Reflecting back, this has hurt me more than I thought it did at the time. So him and his ex and his kids were a family then and he'll never regard me in the same light?
We're engaged to be married. What kind of a marriage is without family?
It's got me thinking about the way he is in general. He never gives a thought to me - never buys me anything, never suprises me with anything, never suggests a quick jolly down to the pub or an evening out at the cinema - never takes me for a meal unless I instigate it. I'm even having to plan my own birthday. For christmas I've bought him a present which I think he'll like. He's since told me that he'll buy a load of computer parts and that can be his present from me. My present from him is a coat, which I desperately needed now - picked out and bought myself and as far as he's concerned that's him done with my present now. No effort whatsoever.
Apart from this his attitude towards everything is wearing me down. He accuses me of not being interesting in his work (I always show an interest) or his kids (difficult when he insists on keeping everything to do with them deadly private). His gaslighting is driving me insane. The other night we argued because I suggested something and he insisted that I meant something entirely different. Even though I told him over and over again that he'd got it wrong he rehashed the same point over and over again about something that I didn't say nor mean. He's not stupid, he MUST have known what I meant but he specifically chose NOT to understand. At one point he stopped and said "oh, so you meant X, Y and Z?" hooray I thought! "yes! that's exactly what I meant!!" I reply. He said "oh well in that case I agree with you" 
but that's what I'd been saying all along! ... anyway a few more things were said and then he started going on and on about the thing that I DIDN'T say again and when I pointed out that a minute ago he understood and agreed with me he got more angry and denied it had ever happened! To this present he STILL insists that it never happened and is continuing to purposely misunderstand what I said.
He has now decided that I have been trying to stop him speaking to his kids and gave a scenario to prove it. I said "that never happened!!" - for a while he insisted that it did but then said "I know it didn't happen, I'm just giving a hypothetical scenario ... " ????? wtf??? he then went back to saying that it HAD happened.
He blames other people for EVERYTHING. He agrees to do stuff for people (me, his mum, his kids whatever) and then throws it back in their face (well no, he throws all of it in MY face as he wouldn't risk upsetting his mum or kids) saying that he's always expected to run around after everyone.
He makes a big point of saying "right that's it, I'm not listening to you anymore, if I want to go to my kids' college events and see how they're getting on I will do." - I have NEVER stopped him doing stuff like this, he just doesn't bother and then either blames me or his ex.
A few months ago he told me that he thought his 18 year old should at least try and get a saturday job. I agreed with him. Last night he spouted out "I'm sick of you slagging off my son! what's it got to do with you if he works or not??" I reminded him that it was HIM who said those things ... he outright denies this and says it was me and he just agreed with me as I've brainwashed him against his own kids.
It's mentally crumbling me.