Is my friend bullying me?

We used to be best friends when we were freshman (juniors now)...then she became friends with a new girl and got into the drug scene.

After she started smoking pot, she began calling me a loser for not smoking and her personality changed. She used to laugh a lot but now she’s trying to act like she’s a hippie or something. She tries to speak about peace and equality but she’s also very judgmental.

The first incident was when I was hanging out with her, her new friend, and their boyfriends. I’m friends with her boyfriend, we all used to hang out as freshman. She said something like she was weird about people touching him so I jokingly touched the back of his head and the next thing I know, she slaps me.

I texted her later and said it bothered me that she did that but apologized and she said she didn’t care and if I was expecting her to apologize for slapping me, she wasn’t going to do it because I need to keep my hands off of her boyfriend (I only touched him once).

So I stopped talking to her and became better friends with a girl I’ve been talking to since last year. We have a lot more in common than me and the “bully” do.
My new friend saw my dad drop me off one morning and walked over to me so we could walk into school together, the bully saw this (she didn’t see my friend get off the bus and walk over, just saw her standing next to my car) and walked up to me and said, “Oh, you and her ride to school together now?” I ignored her.

Her and the girl I was replaced with also have a new freshman third wheel. This girl came up to me the other day and said, “You’re really quiet.” I’ve heard this all of my life so now it’s really annoying. I also didn’t like being spoken down to by an underclassmen, so I just said, “Yeaaaah” and she goes, “Well…you intimidate me.” And I was like “What?” “Yeah. You give off bad vibes.” And then she stopped talking to me.

Me and my new friend don’t have any classes together and we don’t have enough time to talk at lunch, so she came up with the idea of writing letters to each other to catch up. I was reading her letter in the class I have with the bully and she turns around and says, “What’s that?” and I said, “Oh, (friend’s name) writes me letters…” and she looks at me weird and says, “Awww….so when are you guys getting married?”

I didn’t respond.

Is this bullying? It makes me feel really crummy. I also have another friend that was witness to everything she’s done to me, he even initiated the conversation that got her attention about what I was reading.
And yet he thinks I’m being mean for saying I don’t want to be her friend and that she’s rude. I was telling my new friend what she said today and he was so offended that I was talking bad about the bully that he got up and left.

What can I do? If I tell someone she’ll call me a baby or something and if I try to talk to her about it she’ll probably say she doesn’t care or hit me again.