Divorce from husband and visa challanges

Hello, I need help on my situation. 
I came to the Netherlands as partner of my husband who was studying here in Netherlands. After a few month, things got very bad to us. we had several challenges and in our love life.

we broke up and i’m living in another house now but he is allowing me to stay in Netherlands as his wife yet and we didn’t informed IND about our break up yet and we didn’t register our divorce anywhere yet.

At the same time a old friend of mine was also in same situation with his wife in Netherlands but he has his own visa because he is working as highly skilled migrants in Netherlands.
They are living seprately for several monthes now they didn't submit their divorce yet.

Me and the old friend of mine are in love now and we want to start a new life together after all that challenges and problems that we had with our ex-partners.


I want to change my visa now to his partnership. So i need to register my divorce and inform IND now?

Is it possible to change my visa to another partner?

Is IND going to investigate on the reason for our divorces? is it important for IND that we both got divorced here in netherlands?
Do we need to hide our new relationship history from IND?
Should i announce my divorce first and then request for change of partner or what?
I’m so confused and scared. I don’t was to loose this calm and lovely and safe relationship that i have right now. 
We can get married or get the registered partnership to make sure IND believes our relationship.