Advice please

My boyfriend and I have been together for almost three years. Recently, it has been a roller coaster of emotions for both of us. We have been arguing and breaking up almost every week. We have been acting like teens in high school. Pure childish madness between the two of us. We constantly disrespect one another. We do not hold back, we will intentionally try to hurt each other's feelings. Most of the time our arguments are over very ignorant things. Since New Years I have felt differently about him. Some days are amazing but they are few and far between. We decided to break up. Well he is texting and calling and although I reply, I don't want to and I tell him this. It's a cycle that we keep putting each other through. Since we got together it was this way but not as intense and not as frequent; referring to the arguing. 
Today, My mother and I met with my mechanic to fix something on my car. Now I have had the same mechanic for about a year now and my mom as well but today when he looked me in my eyes my heart dropped...his smile was contagious. He made me feel like I was the only women in the world just by the way he looked at me. He was fixing my car and my mother and I left on her car. He called us back to show us something and discuss additional service that was needed. We go and I felt the same way. He was also make it a point to flirt. My mother gets a phone call and is speaking to my sister and says to her something like "I don't have a truck nor do I know anyone with one, we will have to rent one" he immediately interrupts and says she could take his truck. We take his truck and his garage closes at 3pm so he calls me and let's me m ow not to worry about it and to take my time. He stated that he would go home and I can just drop the keys off in the mailbox. Well I was already on my way Jackson I just said ok. 
I am going down the street and saw him and his younger brothers walking home. I stop and he is smiling asking if I was done. I thanked him and apologized and he was just being very kind. 
Now I can't stop thinking of how kind this man is. He makes me "fuzzy" inside and I have NEVER felt this way. 
My question of advice is am I wrong for feeling guilty to my ex? Should I pursue my mechanic? What would you guys do if you were me.