Help! Dating a male nursing student!

Sadly, I have not been supportive as he is constantly texting, calling and seeing a whole bunch of other nursing students. He even tells me how they need him and how he is supporting them. While he does not answer my phone calls or texts. I know he is busy but I can't help but feel jealous and pushed to the side. 

Especially since one of his long time girl who is a friend is a nursing student in the same class and so he spends a lot of time with just her one on one studying even going to her house as he is friends with her brother. He was actually his friend first but became friends with his sister. One day he even told me that if she was here he would have more fun. That she is his best friend and supports him. I want to be happy but I am so hurt and feels like he is constanlty choosing her over me. 

Also, If I go out with my male friend in a group he  gets upset and jealous and acts like a jerk to me. He even looks at my snap and then tells her to look at it. Sometimes she looks at my snap and tells him to look at it. 

His career over me thats fine but it feels a lot like I am just a side piece. He uses her for his emotional support and then me for sexual. If I bring up that I want attention he gets upset and tells me how stressed he is. 

Advice? Thought? Ideas? Support?!😩

Update: I broke up with him!