DBers - Please advise!

Thank you to all who stopped by my thread. I have not posted in awhile, but I have been reading quite a bit - er, more than a bit - Snodderly, you were so right when you said that I was looking for the magic formula. I am trying to stop that.

I could sure use some advice now though.

I will back up a little - so, at BD a little over four months ago and for the next couple of months, my SO and I barely spoke and every conversation that we did have was gut wrenching. About two months later, I found out about the girlfriend. SO does not think this is an "affair" because we were never married (18 years together total, the last few years long distance). As far as I know, they are still dating.

Fast forward to now and I have actually met two of my goals - to re-establish the friendship to the point where he is comfortable spending time talking to me and spending time with me when I am in town. Those goals have actually been accomplished. Strictly following "Sandi's 37 Rules" (which is why I have to guess that he is still dating the OW because I never bring her up), our conversations have been good, almost to pre-BD levels. And he has agreed for us to spend the day together in a little over a week.

OK - now what is my problem then? I think I may have been too good a friend and faked my PMA a little too well.

His birthday is coming up. I know birthdays (and what to do) are very controversial topics around here but my plan was to send a funny card. So I did. Given that we are getting along great, it felt very wrong not to send it. I had not made up my mind as to whether or not I was going to call as well.

Since our phone conversations have been less frequent since BD, I really did not expect to hear from him before his birthday but to my surprise, he called late last night. I answered the phone not expecting it to be him.

The conversation went well and we spoke as two old friends (me, sticking to the Rules!). He asked about my plans for Saturday and said that he will call me after work - he wants to hear his birthday song from me. (Every year, especially since we have been apart, I have sang him Happy Birthday with weird accent or lyrics - I may not be the most affectionate monkey on the vine, but I might be the cheekiest...)I jokingly said that I may not sing one this year. Then he threatened to play back to me last year's song which apparently he saved on VM.

At the end of the conversation he said ILY. I said it back (180 for me!)

The last time we spoke about his birthday - his 40th for which I formerly had BIG plans - all dropped now - he said he barely wanted to acknowledge it. My card had no 40s on it.

Bloody hell, now he wants his song.

Here is my dilemma: If there was no "girlfriend", this would not be a tough decision for me. In the early days, I read one of Michelle's links which described a successful technique as being an unconditional friend during this hideous time and I decided to adopt that as my strategy. However, my concern is that I am still filling the emotional void that the OW cannot yet fill and that by filling that void, I make it easier for him to straddle the fence. I notice that when something goes wrong, either with his family or he's sick, I am the one he calls. Because what new girlfriend wants to hear the gory details? I get them all. I have no idea is he is even celebrating with her - to hear him talk they hardly ever see each other since he says he is working all the time or with his friends or family. But one peice of advice that I have taken to heart is to believe none of what he says.

The other concern I have when I measure up this action against the question: will this push him further away? is that he will cancel our day together. And I really don't know when I will be back in town again so this may be one of my last chances to spend some time with him.

I would love some advice. I am stressing over a birthday song. Sheesh. I just worry that if I am filling the void, OW will "get the credit" if he associates his happiness with her rather than with me.

If he does not call on Saturday, I am off the hook. But if he does....?