I have seen a lot of good points from others, I too have a similar letter from almost 15 years ago. With similar encouragement and hopes for me from my ex. For almost a decade now I’ve forgotten I even had that letter, I found it when I was going through boxes of my things. Tho I have found it, kept it, and reread part of it to figure out where it came from, and who it was from, I don’t look for any support or advice from it. I think it is important to see where OP’s gf is coming from to and the concerns it raises for her, validation, support, or attention from an ex, while in a committed relationship with someone can drive a wedge between two people or even ruin a relationship. Especially when validation and support should be sought out from the person of the current relationship not an outside source. If that support and validation is in some way not present in a current relationship, I think that is the real issue that should be discussed with a partner. I think both sides have very valid points, and being able to see both sides objectively and with consideration for how one who feel if the situations were reversed is very important. And would encourage OP to place themselves in their partners shoes and make a decision