Dena,
You're right on both counts. That was another angle I've approached it from. My sister and I both know about the not so perfect days in our parent's marriage. They've brushed near the concept of divorce a few times in the past, but always shied away in the end. I think they're strong enough, but if they aren't that isn't my fault.
Tysilio,
Thank you. I keep saying those things to myself, that I owe it to myself to be true, but it always feels good to hear someone else agree. I can't own their problems, it's too much, I just have to be good and be myself.
As for my sister, it's odd. She's younger by about 3 years, but in a lot of ways she is very protective of me. I don't think she's trying to guilt me, she's just trying to make sure that I've considered every angle and making sure that I'm not acting in haste. She's also scared, and I totally get that. She's been a hero throughout this process, so I'm giving her the benefit of the doubt when she gets a little worn on the edges.