Come and tell me I am an awful daughter, I know I am 
My parents divorced when I was 7, me and my siblings ended up with my dad as my mum left to move in with the OM she was seeing. My DF did a great job raising us, it was the 80s, men didn't really do that kind of thing, he really made it clear he wanted custody.
She married the OM, my DF remarried too. DF is still married to his 2nd wife but my DM is currently single. Relatively recently she moved from the part of the country she had lived in for 25 yrs to the part of the country where we live. She actually lives about 10 mins away now, which is possibly a bit too close for me but we weren't exactly consulted on the move IYSWIM.
DH and I have kids now, and she is a great help, comes over one night a week to do school run, often helps at weekends, sometimes has them for sleepovers etc. the kids love her, she loves being close to them.
I think the problem is with me. In her efforts to be extra helpful, I sometimes feel there is an implied criticism of my parenting eg: she will buy an item of clothing for the kids which is completely unnecessary but SHE clearly thinks they a) need it and b) that I am not providing it. It's lovely when she buys them little treats but things like clothes, shoes etc I feel are our responsibility & I feel she's treading on my toes. I know this is stupid and she is trying to help.
The other thing is that I find myself increasingly cross towards her as my DC approach the age that I was when she left. Looking back at it now, I think she was really selfish and I can recall instances when she really just did what she wanted eg: we would see her in the school hols but one year she just decided to go abroad for the whole6 weeks, meaning we didn't see her & my dad as stuck with the long summer to cover on his own while working FT. At the time I didn't question it but now I am. I can't understand how she made those decisions.
It seems unfair to me that she was so absent and selfish when I was a child and yet now she gets to be the grandma who lives down the road and sees the kids every week. The other GPs see us much less often due to distances involved.
Anyway, sorry for the rambling. The main point is that after too much to drink last night I had a terrible row with her about all this. I was so so cross. I felt like I really wanted to push her away. I don't want her living so close to us and so involved in our lives, I don't feel she deserves it and I resent the implied criticism of the job I am doing as a parent when she basically absconded from the role.
I called her this morning, we talked, I apologised, she cried. I am not sure where to go from here. I feel like I need to put distance between us but I know she would find that heartbreaking.