Interfering mother in law!!!

im wondering if anyone can give me some advice.been going out with my partner for nearly 7 years and wehave a 5 year old daughter currently ttc(maybe) in that time his mum wont stop interfering.its really pathetic and have threatened to leave my partner so many times i just cant stand it anymore.she just ... about me all the time and talks c rap about me and tells me what i can and cant buy my daughter.other day i bought my daughter clarks shoes for school i may add they last longer. next day every1 in my partners family ask about them and the cost.ahh!!!
my partners brother has children and when they are in my daughter gets ignored she also plays a lot of mind games with me.i dont know what to do i stayed before because i loved my partner now i dont feel a thing i just dont know what to do.when we are apart we always seem to get back together i just want a peaceful life.my mum says if i love him and want to stay with him ive got to put up with it but im totally drained with it.anyone else had the same please help xxxx