Is my girlfriend still bi ? should i stay with her ?

well me and my girlfriend have bin together for nearly 2 and a half years . but this past 3 months she has started texting alot of boys but she lies about it.it started when me and her split up 2 months ago abd she never spoke to me for just over 2 weeks. 2 days after we split for a so called "break" (she called it ...) she went out with a boy 2 days after we split then 5 days afeter had with him then 2 days after that he dumped her.. me and her started talking a few days after he dumped her but as i was texting her i was still under the impression that she was goin out with him as she told me she was with him. but i found out from my mate that he actually dumped her and then it clicked she only started talking to me because he dumped her but me and her got back togethe now all i can think about is her and him even when me and her are doing stuff together it on my mind so i have to stop as it puts me off. but aswell as that she is texting other boys it started when i looked at her phone and saw she was texting guys everyday. it not the face she text guys it the face it every day and she replies to their text every min but with me i am luck if i get a text every 10 minutes. also she never calls me no more and if she calls me it only if we are arguing and i not text her back.. i used to phone her but she suddenly came out with she found it annoying me calling her all the time so i stoped and told her she can call me but it never happens but yet she will call other guys and sit on the phone to them for hours.. i just feel like she dont make time for me like when she text boys she will say i geting ready for going out or somenthing like that but if i text her while she getting ready i get told i am annoying her and i text her far to much what you think ???