husband has many female friends, is that normal?

You’re not, especially if those friends who asked him to not invite you are females. They have to know that he has his own family, by inviting his spouse is an act of respect regardless whether or not the spouse wanna join. I am super introvert so I hate gatherings, especially with a whole bunch of strangers (my husband’s friends) so I’ll always reject to be there, but at the very least, I know who he is with. Talk to your husband, raise your concerns, especially those red flags with his friends (particularly female friends). He should stand up for you, albeit his kind character because you are his wife. Basic respect towards your friend’s spouse and maintaining a safe distance with your married/INR friend (opposite gender) is common sense.