I really need some advice...
I've been with DP for about 15 months - he doesn't live with us but stays over several times a week. I have DS(5) and he has his own DSs - 6 & 4 - I'll call them DSS1 & DSS2 - all the DCs get on well and have fun together - they stay over once a month and we all go out together often.
Last week we went away. DSS2's behaviour was challenging. On the journey there, he got cross about something and began chucking things around the back of the car - toys, shoes, water bottle
and hit and scratched me when I held onto the things he was trying to throw. DP looked embraraased but didn't do anything. He eventually stopped the car when DSS2 took his seatbelt off while we were on the motorway.
This got worse - no please/ thank yous from either DSS, general stropiness at not getting their own way and by the 3rd day, they were saying my DS was naughty (he wasn't), stupid and couldn't play with their toys. DP got increasingly cross with them and snappy with me and cried because he didn't know what to do. We talked about what he wanted me to do and he said he wanted me to continue to support him and to have the same expectations of DSSs as I DS. He asked what I'd do and I said be firm and consistent (which is what I'd do at work).
Over a few days, it became clear that DP wasn't actually going to deal with the problems at all - he seemed to let me do it then take his boys to do nice things (pub, cakes etc) when they'd been quite rude/ aggressive (hitting DP when we were out, screaming if they couldn't have a toy, blocking other people trying to go into the public toilet and refusing to move when asked etc). I got fed up with feeling like I was nagging them, so I stopped.
By the last day, DSS2 (who weighs twice what DS does) had dug his nails in DS's leg, leaving nailmarks and grabbed his collar then shoved him over (for no reason - I watched). DP saw but just walked DSS2 away - he didn't say anything. We got in the car and came home. I feel realy angry with DP - like he didn't address the issues and he let his DC hurt another child (maybe I am overreacting because it was MY DS who got hurt
) and then did nothing
. At the beginning, I felt like we were a family. DC WILL argue a bit and DP & I dealt with things together. But as the week went on, I began to feel that DP wasn't interested in being a family at all.
When we got home, I took DP's key off his keyring and haven't spoken since. 
I don't know what to do now. It was a hellish week away and DS doesn't want DSS's to come over anymore. I just wanted to be a family. I miss DP.