I don't think Dima had ever a relationship with Sogdiana. They were just good friends. However, they look cute together and I wish they would sing together.
Vika was angry at Dima when he was in Fabrika 6 because of Sasha Gurguva and not Sogdiana (they annoyed eavh other a lot and it seemed like they like each other). Dima broke up with Vika, I think, a bit after Eurovision 2007 and Sogdiana was already married then (I think)

That's right, but I know he doesn't like her. I can see it from the way he talks about her. He told that she never agreed to wash dishes when he visited Fabrika 7 participants. It seems that he really didn't like it.