Should I let our friendship go?

I was stupid and I flirted with one of my ex-friend's husband. I'm married too and we both knew nothing would come of it but, I guess my friend didn't. It's been 3 yrs since this happen and we have both had children since that time. I've grown up alot since this time and I really miss her but, I don't know how to regain that trust. Is there any way to rekindle this friendship? Any suggestions?