What to do about annoying ex?

wel my ex is constantly texting me saying he loves me misses me and asking me things like would i break up with my current boyfriend to be with him and stuffs even tho he was the one who dumped me a day before valentines by text! he has also been pestering my friends too. he is also the type to be constantly looking for a girlfriend and when he has one he wil treat her bad saying things like id rather be out with my friends than you and lie a lot like he said to me that he wanted to kiss other girls but apparently said that coz he wanted an excuse for me to break up with him. however the boy am with now is great. its just my ex wont leave me alone! he keeps saying things like do you remember the good times and your cute and that but i think hes just doing it to say he has a girlfriend and play them like he did last time even tho he claims to have changed. so any advice on wht i could do? ty x