How do I show this?

Hey guys!

I'm working on a contemporary romance where the hero and heroine both became successful via country music at a young age--he as a singer and her as a songwriter. (I posted a thread about this idea, in a general sense, a few months ago.) Despite him being a couple years older, they developed a complex online friendship which (unknown to each other) resulted in them having feelings for each other. Unfortunately, things happened that caused the guy to blame the girl for something really horrible and they drifted apart. Also, she wrote under a pen name and, while he *did* know that, he never found out what her real name was. (Her father, a big record label exec, forced her to remain hidden behind a name if she wanted to write because he felt the pressures of being famous as a teen would be counter productive to her actually being focused and successful. Also, he can't stand the country singer and there's a ton of history as to why.)

Anyway... The story takes place several years later where circumstances have them stuck living in a house together for a month during the summer. He's never gotten past being upset with her (and still has no idea who she is) while she has never really gotten over him. Tried to move on, sure. But having him with her is driving her nuts.

My question is this: what suggestions do you have on how I can show their past so that what is happening in the present will have the right impact? I do have them think about each other when appropriate, or think about things that happened, when appropriate. But is that enough? I think that my readers will get more out of this if they see not only what these characters are trying to gain here and now, but also what they had, lost and could regain if the heroine has the courage to let him know the truth, and if the hero has the integrity / compassion to get past the hurt he experienced in the past.

Since there correspondences were via computer IM / e-mail, this doesn't seem to lend itself to typical flashbacks or dreams. I have thought of letting their song lyrics go between chapter sections, or showing a couple really key IM exchanges this way at appropriate times during the course of the story, but those are both relatively unconventional approaches. I know that I can also have them look at their chat logs or old e-mails if I absolutely need to, but I don't want to abuse this, either.

Any thoughts and suggestions are welcome. Thanks for your time and have a great day!

Thanks so much, guys. I'm fairly in love with the idea of weaving stuff in but I wanted some feedback on whether that seemed too much like a gimmick. I've seen it done a few different ways, but its not overly common.