Really struggling with my 9 year old ds (only child) at the moment. He can be cheeky and boisterous but generally his temperament has been lovely since he was a baby. Over the last few months I've noticed that he doesn't seem his usual happy self. Recently he lashed out at another child which was upsetting and he has been quite aggressive towards others. My parents have commented on his behaviour, my mum doesn't think he's overly happy at the mo.
To give you an overview, we left London two and a half years ago - his dad is still up in London and we're about 70 miles away. He sees his dad three times a month during term time (ds goes to London one weekend a month and his dad comes down twice a month for a day on the weekends) and we share the holidays. I know he misses his dad terribly and every time he comes home after seeing him, he tends to lash out at me.
I was unwell 18 months ago and as a result, we moved in with my parents whilst I got back on track. Things are slowly coming together and we should be in a position to move out again by the summer. It has been difficult at times staying at my folks, as much as they are wonderful grandparents and have been a fantastic support to us both, we are all in need of our own space.
Every day he comes home from school and there seems to be a problem with one of his peers, the same names do come up but I honestly can't remember a time when he didn't come home and say so and so has done this today.
He constantly answers me back, speaks to me like dirt on his shoe and throws a paddy if I ask him to do anything. He resents having to do his homework - it's a battle every time.
On several occasions when he gets so frustrated he tells me that he wants to hurt himself. This is incredibly upsetting to hear and makes me feel like I've totally failed him. 
I'm at my wits end and it's making me really sad/want to burst into tears regularly. I keep getting told it's just a phase, it's his age etc etc. I've tried talking to him and he tells me that he's stressed at school. His school is quite pressurised and I am wondering whether this is the root of the problem or whether it's a combination of the factors above. I find it hard talking to his dad about the problems, we don't have the greatest relationship although we are in a better place than we've been in a long time. It's incredibly tough talking to my parents too, largely because we are all on top of each other and no doubt driving one another crazy.
Anyone else experienced something similar?