My girlfriend of 3.5 years gave me a horrible STD, cheated on me five + times and is now marrying one of the douche's she cheated on me with, should I forgive her?
Forgive her? No! You should be sending her a bill for the Doc visits to the address shared by her and her new hubby. You should be gift wrapping all remnants of that relationship, including any "personal" items of hers, you might possess, to her husband -requiring his signature for drop-off. You should be fucking as many of her best friends as possible.
However, you could just learn from your mistakes (3.5 years/cheated 5+ times...seriously?!), make a plan to move forward and burn all those mementos. Find what's left of your nuts and add miracle grow or something to those bitches. Don't ever let anyone treat you like that. It is ridiculous and unnecessary. As for the ex. She doesn't need your forgiveness, she's moved on. So should you. Consider it an early birthday present. Someone else now has to put up with her shit! Ok, ok... you can still signature mail her undergarments to the hubbie for shits & giggles... but seriously... get over it already!
Dear So-and-So,
There's this girl who gives me mixed signals. She told me at one point that she was interested. Since then, it's like she doesn't want to outright tell me that she's not interested but acts like/says things that tell me she pretty much doesn't have the slightest interest in pursuing it. She plays at her original statement real nice. We talk about it but nothing comes of the conversation except for a whole lot of "Days of Our Lives" type shit like, "I just don't know what I'd do if you weren't in my life." What should I do?

Dear idiot, enclosed you will find a dollar. Go to the corner store and buy yourself a clue. Any girl that expresses interest but doesn't follow through is NOT going to follow through. You can have random, drunk philosophical conversations about it and never change a thing. The conversation is designed to stalwart the whole situation. Either she meant it at the time but has since changed her mind or she lied. Sounds to me like you're both emotionally stunted.
The girl isn't interested. For whatever reason she took pity on your sorry ass and expressed (ie...mixed signals) a fascination with you, even feigning sincere interest in pursuing a conversation regarding the matter without making the situation any different or any less confusing. You will never have a shot. The first step is admission. The next step is the curb.
After all, you can always look at it this way, if she doesn't want you than maybe it's all for the best. Maybe she doesn't deserve you. Maybe you're too something awesome for her and she knows it. Maybe she is a bitch who's just playing games. Maybe she's just not interested but is playing the 'high' road. Bottom line, if she doesn't want you, you're wasting your time. Better to realize that now, than much later.