What the f-ck do I do?? (Outing of transgender identity)

One of my best friend is trans (ftm). He came out to me in April. He came out to his mom in May. She said "I love you" and stuff but she still calls him his birthname and feminine pronouns. She also kind of makes fun of him for expressing his gender the way he wants. Like the other day he said she told him "that's disgusting" about having a bulge in his boxers. And he's made fun of him binding and stuff too. Idk it just seems off even tho she says she's supportive.
He's been dealing with that. It's hard on him but he manages.
He came out on Facebook in June and changed his name. He hasn't had any major conflicts with that and most people are fairly supportive even if they don't completely understand.
Last night he got a call from his grandma. She said something like, "did you change your name on Facebook?" Or why or something. I guess another family member showed her his Facebook cuz he had her in his profile picture. So when she mentioned his name, he hung up on her and threw his phone across the room. He said later that he wanted to burst into tears but couldn't because we were at a group sleepover. Me and him went on a drive and listened to music but didn't talk about it. He texted one of his older friends for advice and I don't know exactly what she told him. He said she kinda had suggestions but didn't want to specify further. I didn't push him.
I mean we got through the first night but I'm sure he's hurting a lot and really scared. He's posting a lot about self harm and suicide on his tumblr which isn't new but it definitely seems worse than usual. I'm sure he's gonna end up self harming in the next few days, but what I'm really worried about is a suicide attempt. I don't know if he even has enough energy for that but I'm really scared. He hasn't attempted before that I know about but we have only been friends since last April and hes been struggling for a while before that.
How can I support him and make sure he's okay? I don't know what the f-ck to do.

 

No you don't understand. He's in counseling. His mom knows he's been struggling with this stuff, but she's not gonna be any help with this specifically sice she doesn't really support him. Adults can't fix everything, not even parents. Sorry but it's the truth. She'd probably tell him to get over it or he brought this upon himself for "choosing to be trans." And regardless of who I go through, it's gonna eventually land with his mom and then yeah. I can't do that. It'll make things worse for him and then he won't even feel like he can trust me.
I need to know how I can support him and/or where I can get him support.

 

What are some online support forums or groups for ftms?