<human>: Can you give me the gist of the text in a nutshell?

Now, I'll preface this by saying I actually have a happy, functioning, lovely relationship. My boyfriend is only 2 months younger than me (making him 19) and we've been together only about 4 months but we've known each other for longer and we've been through a lot together. The only problem is that I get insecure about stuff. I used to have severe depression and anxiety and my boyfriend's seen me at my worst and stuck by me but that sadly doesn't help my insecurity and lack of self confidence and though boyfriend says he's not bothered in the slightest and doesn't notice it, I'm worried it will hurt the relationship.
The main thing I'm insecure about is a girl. My boyfriend used to be infatuated with a girl who didn't reciprocate his feelings for about 6 years or something, she was part of the reason we couldn't be together at first and I had a very upsetting few months because of that. He's over her. Apparently he hasn't liked her for a while now but I just feel so insecure about her. I feel like I'll never measure up to her or something or that when my boyfriend goes back home he might fall for her again.
The worst part is that I know I'm being paranoid, irrational etc but I just can't shake this one insecurity. It just won't go away no matter how hard I try. It's not present in day to day life or anything but I'm worried that I'll ruin the relationship if I can't let go of this. It's in the past and I should know that.
<bot>: Insecure girl with no self confidence worried about a girl her bf used to like and if she's hurting her relationship in general.