Am I just being jealous?

Me [29M] and my girlfriend [25F] have been together 3 years and the last 18 months her friend has been driving a huge wedge between us, but am I just being jealous?

I literally cannot spend a minute of time with my gf without her friend ringing and sitting on FaceTime, Valentine’s Day was spent with her on the phone and they play video games together all evening after work whilst on FaceTime and are literally in separable. Her friend is bi sexual and has often made sexual comments which my gf just laughs off and when I’ve brought it up it’s thrown back in my face like I’m over reacting and I’m jealous and I’m not the jealous type, whenever she goes out I never even bother to text, I trust her fully and let her do her but I cannot get over this with her friend.

She never bothers to plan things with me despite me asking, I’m always up for a day out, plans weekends together with her friend but then texts me constantly while out with her, her friend will ring up and say “I thought it was my time” when she’s with me, she threw in her face on Valentine’s Day “go and sleep with your boyfriend” talking about me and is just generally obsessive, but when I’ve brought this up it’s like I’m gas lighting myself and being jealous. Genuinely considering just walking away and ending things tomorrow with her as she can’t see an issue. I literally cannot remember a day we’ve spent together without her third wheeling honestly.

Advice please fellas - I know if one of my mates where on the phone all the time or I was at the pub every day I know I’d be getting a bollocking lol.