Hi Ahlbi and welcome
This board is a great place to get help and support from other like-minded people. I'm sure you'll find a lot of inspiring/motivational stories out there from other members who have battled their own weight issues/are still struggling with their weight issues. Jump right in and have a read through some of the articles and older posts and just start interacting with people - everyone here is really friendly and encouraging. There are also seems to be quite a few new members on here who are also mums looking to lose weight, perhaps you could team up with some of them and encourage each other!
I'm sorry you had a rough two years, but I'm sure 2012 is going to be your year! I was over 100kgs when I first started losing weight, so you're already at an advantage there
Also, you don't need to have an expensive gym membership to lose weight, all you need to do is eat as healthily as you possibly can and try and incorporate a little exercise into your routine. Perhaps you could ask a friend/family member/partner/neighbour to watch your children in the afternoons while you go walking or jogging? When I first started losing weight, I used to power-walk for an hour or so a few times a week and that really helped. Best of all, it was free! Currently I'm really into swimming, which is great for weightloss. It's also relatively inexpensive, about $4 per visit and you can swim for as long as you'd like.
Good luck with everything, let us know how you go
If you'd like more help with anything in particular, just ask!