Boyfriend flirting

Okay, so me and my boyfriend have been together nearly 3 years. Within the first 3 months of our relationship he’d already checked out countless of half naked girls on the beach. I don’t care about window shopping but when I’m stood there half naked to receiving no attention at all whilst he stares at this girls ass is a bit of a let down, especially on our first holiday.

Secondly, we have a part time job together (when we were 16 & 17 he needed a job so I got him a job with me) we both work in separate compartments however every time I had to go into his compartment he was always there flirting with girls, making them laugh and then as soon as I walked in all I’d get was “alright” and that’s it!

He’s just an all round flirt and i feel like I can’t take it anymore. Some people may say I’m overreacting but try being in a relationship where he flirts with everyone bar you. Your self-esteem and confidence drop right down. Ooo not to mention he lies to me constantly!!! He lies to my face until I catch him out and then blames me saying I’m the reason he lies. Someone help me before I lose my mind!