Since you seem to be upset by this, I would first advise you to go to Islamic Careline in Fordsburg for premarital counselling.
It's great because they help you discuss whatever is bothering you in a safe manner and also gets serious topics out of the way and allows you to see where your future partner stands on certain issues. They first ask you to fill in a questionnaire which has all sorts of questions regarding children, finances, etc. like the IMPORTANT day-to-day things of marriage including the affectionate ways
It's also nice as it lets you air your concerns in an appropriate manner and also lets you see if there could be major issues in your marriage later on.
Please don't delay it. Call them as soon as possible! 011 373 8080.
I wish I had done this before as I didn't realise a lot of things about myself until 3years into marriage and I think I would've been better equipped for marriage if I did the counselling before I was married.
It's very difficult to live in a home where your mother in law is cold towards you. I would suggest discussing this with your future husband and I think this may be the safest manner to do so. However, if you can't attend the counselling, then I would suggest discussing it with him immediately. Be diplomatic, say, 'I notice that your mother doesn't really discuss things with me in a nice and warm manner and I was wondering if she doesn't like me? I'm really worried as we're going to be living together and I don't want any of us to be upset or frustrated with each other while living in the same home.'
Maybe try and spend an afternoon with your future mother in law? Go on a shopping outing with her or have lunch somewhere - just you and her - and see how she behaves with you then.
May the Almighty help you in this big step in your life. I wish you all the best.