Lance...glad to hear you're feeling better and I really do hope that you are able to speak with your friend soon.
I know you've said that you've talked with your partner about the guest situation, but from where I sit, it doesn't look like he quite gets the seriousness of it! I mean...you left for goodness sake! That's pretty serious!
If you're anything like me, then it must feel like he's choosing the obnoxious house guest over you right now...that's how I'm feeling in my own situation...and it hurts.
Please try and write down your feelings and possible solutions so that when you talk to him again you don't miss anything.
Still sitting with you.