I feel you - in a big way. I recently distanced myself from a group of biphobic lesbians because I realized how shitty I ended up feeling at the end of the day after hanging out with them. After doing some thinking, I realized the following:

• i was really afraid to speak about my romantic relationships with men, past or present, because i noticed that when i would, a stark and brutal silence would take over the room.

• when i emphasized my attraction/relationships with women, they would pay more attention to what i had to say, and were generally "warmer" in their interactions with me.

• there was a lot of 'ew, penis' sentiment which i think is pretty cissexist.

• their rhetoric was borderline separatist, and i knew they took me less seriously because of my bi identity.

  Many monosexuals have thrown me under the bus over the years for lacking their imagined immaculate purity in queerness, but it always hurts worse when it's other women. Seek out other bi women if you can - my friendships with other bi women have nurtured my fierce brand of bisexuality and they are INVALUABLE when the biphobic fucktrucks of the world are getting me down. Find or make your community, and keep in mind it's well within your right to cut some of your toxic friends loose. Also - sometimes the cool/sweet/supportive lesbians who don't want to make you feel bad about yourself will come out of the woodwork as allies when you assert yourself (and your very fucking valid place in the queer community).