God loves us all and wants to see us redeemed, I agree with that...
However, Jesus Himself overturned the tables of the money changers in the temple...unconditional love does not mean blindly accepting another person as a part of your life without expecting them to do the work to make amends for the damage they have done...
And no your W did not "Mean" to give you STDs but going outside of your relationship and sleeping with someone else then sleeping with you means, her actions are the direct cause of your STD! And if the other guy does not have it, I am sorry to say but there is probably another guy out there that she got it from, whether before or after you two got together I don't know....but it had to come from SOMEWHERE...
Nobody wants you to just give up but you need to have your eyes wide open to accept your current reality and deal with the way things ARE, not the way you wish they WERE...