How many of you have acquired your husband's friendships of the opposite sex (aka. his girl friends). Have you had any successful "transitions"?

I have had some success in several friendships but there is one in particular that just seems a bit too much for me these days. I think mostly due in part to false expectations of what she wanted in me b/c of her friendship with DH (she thought of him as a best friend/brother, he thought of her as a borderline acquaintance/friend). When I married DH, she told me that whomever he married, i would be their best friend and to be honest, it threw me off. And I'm feeling a bit badly since I am unable to fulfill her "expectation" because in short, DH doesn't like her at all because of her behavior and pettiness and he doesn't want me to confide in her at all. So because I am surface level with her, she resorts to petty drama, etc. Just wondering if you all had similar situations and advice on what I should do.