I am a feminist, always have been, even when I thought I was male. I hang out with women when I have a choice, and I am accepted by them. Accepted as what exactly, I don't know, and I don't ask. I'll take "accepted". They treat me as a woman, and I am good with that.
Although I am a feminist, I choose to avoid feminist groups for the reason you described. Not all women are like that, and not even all feminists. There is a subset of feminists called TERFs: Trans-Exclusionary Radical Feminists. They hate our guts. The trouble is that you don't know when joining a group how many of them are TERFs. They might be a small minority in some groups, or a majority in others.
I am sorry you had to find out about them the hard way.