Opinions please, I'm having friend trouble?

We have been friends about 8 years and everything was generally ok until our children were born (we both gad boys 5 months apart.)

She became boring, absolutely no fun at all. I gave up in the end in trying to get her out enjoying herself. Then the problems really started three years ago.

She basically started pushing me out whenever we were out all together. She'd turn her back on me, ignore me when I spoke, anything to make it so she was the centre of attention. Me being the decent and calm person I am, said and did nothing just took it with a pinch of salt knowing full well the next day she would basically be my best friend again. Then she started with money. "borrowing" but never giving back, she owes me more than £1000 in total if I'm honest. £30 here, £50 there...it's all added up. I've never borrowed anything from her though, I never would.

Then there was the getting me to collect her from work then take her to collect her son from her childminder because her partner works nights and they only had one car at the time. This happened twice a week for about 6 weeks. Then instead she started asking to borrow my car. Then she started having me look after her son while she went to the gym for an hour. Then it was look after her son all day on my first wedding anniversary. The kids? Last birthday my son got nothing for his birthday. I had my birthday missed. My husband has had his birthday missed twice. If I missed ANY of their birthdays, there would be utter hell to pay. You can't rely on them for anything other than to let you down or break plans at the last second yet I am expected to keep every single word.

The last time I saw or spoke to them was the 30th July although I did text her on Friday that week (3rd August.)

She sent me a text message in Thursday saying "I don't hear from you anymore" and I told her the truth, this past week I've been chasing my five year old around keeping him busy, trying to see my husband who works 15 hours a day 7 days a week to make ends meet and I've been having a hard time with my pregnancy. I got no reply, I tried to call her twice yesterday but she rejected my first call and ignored my second. I'm sick of her now as everything is always my fault. I'm just trying to actually understand what I've done wrong really, and to ask how it looks to everyone else?

I've been there for her through thick and thin and got nothing in return, am I actually at fault here? Sorry people I've ranted a bit!