I would sincerely appreciate if you can shed some clarity and objectivity on this, as I feel very unfairly treated and deeply saddened to move on in peace; it is beyond my rational understanding what really happened to my boyfriend in such a sudden way. Many thanks for your attention and time.
I'm so sorry this happened to you -- I know how disturbing it can be, to be cut off without a word like that. However, you need to consider this a benefit -- you have been saved from being committed to a selfish, inconsiderate and uncommunicative partner.
Your relationship never really had a chance, because it progressed too fast to develop an infrastructure"-- the trust, teamwork and basic necessities for building a relationship. In the future, you can avoid being so hurt by going much slower, taking enough time to find out if your prospective partner is trustworthy. The Unofficial Guide to Dating Again will help you avoid falling into this trap again.
Please don't waste any more time trying to get answers from this man and his brother. There are no truthful answers you can get. Either he got cold feet, he didn't mean what you thought, or he's met someone else. The answer you have gotten is that he's not a good candidate for a commitment -- with you or anyone else.