Can I get back my ex girlfriend

My girlfriend who I have been in a long distance relationship on and off for ten years left me for another guy this woman claimed she wanted a future with me I was ready to move up there with this year because my job was ending soon she throws this dude in my face talking about he gives her money every payday and I respond with like I have for the past three years she cant respond I ask why is she taking her son away from me after she promised no matter what happens between us I ask why choose her him over me she says cause she can. In the past she's cheated on me and I never forgave her for it and I hold it against even though I loved her I'll always be apart of his life now she won't respond to me when I ask can come pick him up and spend time with him she's ignoring my calls and texts I lose my temper one night and text her she says I'm just mad because I gave her son a gift and she's not giving attention she says I'm annoying by blowing up her phone but she did the same thing when I broke up with her many times I've tried apologizing to her but she won't respond I asked her does she want me out of her she tells me to leave her alone but when I ask why she ignores I would leave her alone if she tells me why I'm tired of this on and off relationship the only reason I stuck around because I grow to love her son how can I move from this nightmare I gave my all to this relationship only to get stabbed in the back