Baby mama!!

Vikki • 25, Newly married, added two children to my life ages 12 & 7. Considering my own child next year.
I've been married to my husband for a year & been around his son for two years now. I have and still do everything I can do for his son when we have him. When he is with us he is very respectful & wants to be around me. But he just started football so me, his dad, his mom & her husband all come to practices so when his mom and husband are at practice he acts like he doesn't even know me or his dad. I take this real personal because I treat do everything I can for his son. How do I deal with this because I'm sure he acts this way because his mother brain washed him and makes him feel like when she is around he can't speak to us?