My ex girlfriend is still being controlling towards me?

We're both in our second year of university although we got together quite early on at the start of university and we were together for just over a year. We were so happy together but then her mother got involved, who was an absolute control freak and would just use her daughter and treat her like a slave and ruin her life. She controlled her husband and other daughter too but they just used to bow down to her every command.

I spent a few months away last Summer with her and her family and some of the things I witnessed were scary. Her mother didn't speak English although obviously being together at the time, she'd tell me her mother was saying all these hurtful things about me and my family when her mother had never met them. I tried to get her to come back home with me and get away from this control but she wouldn't. She was being bullied and manipulated everyday but there was no separating her. Anyway I went home where after that I just noticed this huge change in her, she was also bad mouthing my family to me (Despite them giving her everything she could ever dream of) and I stuck by her for a long time hoping she'd snap out of it but she didn't. She actually became her mother. Sometimes she looked like the double of her, although mainly it was just her behaviour. It scared me though, I felt a little tied down because I loved her to bits but also worried she was going to turn more into her mother, into this control freak and this manipulative person.

We agreed just after new year this year that we'd break up so long as we could stay friends. This was a mutual agreement but shortly after, she started talking to me more and more about this guy from her work, then all of a sudden she distanced from me a lot to stay up until the early hours of the morning messaging him. We were living together at the time (a long story but she was living with me and my family quite early on into the relationship due to her old place being unsafe) but I suggested to her that if she's moved on and we've broken up, then there's no point us really living together anymore. And she agreed and found somewhere to live a few weeks ago.

Since then, it's safe to say she has gotten closer with this guy from her work and she admitted she has some kind of feelings for him. I was absolutely fine with this, as just because we didn't work out, doesn't mean she wouldn't work out with anybody else. But I recently became close with another girl in our university class, she's been showing an interest in me for just over a month and it's safe to say we've gotten closer. Yet my ex girlfriend is now getting funny with me for 'ditching' her to go and talk to this new girl.

I am trying to make the effort to be equal with everybody, and I do feel really bad for my ex as she has nobody whatsoever in her life apart from her manipulative family back at home who she thinks loves her. I want to stick by her and be a friend to her. But at the same time I'm feeling tied down by her. I feel like I have to spend every single minute of everyday with the way she behaves. Yesterday she went back on her word and said she's not having feelings with this guy from her work, But they're going on a date today! But she is classing it as a friends date, nothing will come of it etc. I seriously don't mind what it is, I just wish she'd stick by me regardless. If I was to even get with this new girl, I can't be expected to ditch her for my ex girlfriend..And I wouldn't mind but I did spend some time with her this week, but clearly it wasn't enough time.

But here is my dilema. She might be my ex girlfriend and we might not have worked out in a relationship but she's still a really good friend who'll look out for me, but do I really want to ditch her for some girl I haven't even known all that long? In that respect, no I don't but I feel it'll come to this. I feel like I'll lose one or the other, and this girl could be the one for all I know..

Any advice?