I know it's confusing which way to Chicki. Make him miss it or try to be there. Hard to tell the right path sometimes.
However, my feeling is, not acknowldeging his birthday is just mean. There are certain acts of kindness that just make us good people. Don't loose those.
Treat him more like a brother than a H. Would you get your brother a nice card and maybe a small gift or if nothing else a text or email wishing him a happy bday? Probably. To just ignore it all together just sends a signal of wanting to be mean to him. My 2 cents.
