<human>: So to give some background, I [27M] have never being in a relationship or have gone on a date before. I grew up in a small town church where everyone pretty knows each other.  After growing up in same groups and spending a lot of time with Emma [26F], I developed strong feelings for her, however, I did not make any moves or told her about how I feel. In the end she ended up dating another guy and got engaged, which I am still somewhat sad about but has accepted.  

Recently, her sister, Anna, [22F] has shown signs that she is interested in me. I am considering pursuing a relationship with her, but am worried about how to approach this.  I feel that if this relationship were to advance, I would eventually have to tell her that I had feelings for her sister, which may make things awkward. I would also always be comparing her to her sister, who I was attracted to.  I should also mention that from what I see of others, it's not uncommon for people tie the knot after dating for just 1-2 years around here, so it could get serious really quickly.

So, should I not say anything, bring it up right away, or wait until later on?

To conclude, I don't know what I am doing and would appreciate some opinions, since I have not shared this (nor anything personal really) with anyone before.

Could you distill the essence of the text into 1-3 sentences?
<bot>: I am thinking about dating a girl of sister who I was interested in. Need some advice on how to approach it. Thanks to all who contribute!