How do I convince her we are not doing anything wrong?

A number of months ago I found out that my gf cheated on me with her friends bf. As a result, her friend and I kind of leaned on each other because the relationship had been going on behind our back for sometime. Over time we became close. We had no contact with our exs until my ex found out I was dating her friend, which they no longer were. She was furious about this and said her friend was betraying her. I ask how considering what she did. The problem is that my new gf, my exgf exfriend feels guilty. I keep telling her she has nothing to feel guilty about and tell her how I love her more than anything and she shouldn't let her destroy what we have. I don't know if this took, she seems still hurt by loosing both a bf and friend back then because of all the betrayal. Is there anything else I can do to help us move on together and finally put this in the past?