Confused guy asks: Should I marry my ex-girlfriend’s younger sister?

Confused guy asks: Should I marry my ex-girlfriend's younger sister?From a male blog reader:

I have a girlfriend I loved so much, I set her up and gave her everything she could ever need, foreign trips, a house of her own and a car and even set up businesses for her siblings
Things went bad when I invested all I had and loans into a buisness and it went bad that was few months to our wedding . We had to put it on hold and all so I could get back on my feet. Had to sell my houses and cars to pay the bank back and moved to my girlfriends place
P:S I bought the house for her
While trying to get back on my feet, she started cheating on me, called me names and told me I was too broke to marry her because she was the one paying all the bills, a year and half passed and she sent me out of the house that she couldn’t cope again, her younger sister became my saviour, got me a new place, a small car and responds to my needs. 6months ago, she had this messy breakup and we have been together since then tho our relationship is undefined . She’s all I want and more in a woman. I am back on feet now
P.S without her i wouldn’t be back on my feet now. We took a loan from the bank with thier father’s house documents
I love this girl , we are not official because of her sister, family and what people will think. I asked her if I could post this .. we need your opinion. Do we get official and get married? If you were in our shoes what would you do? Please opinions