Ok this forum is a new one for me, but here we go.

Im a 26 year old military member and recent divorce'. I still remember the first relationship I ruined by cheating. And the dozens since. For a long time I simply didn't care. I even managed to marry a woman like me, who cheated as often as I did, but since we didn't talk about it we pretended the other wasn't doing it. Then she got pregnant while cheating, and logically I asked if there was a chance the baby wasn't mine. She said no, so I did the dad to be thing, all of the pre natal's, baby shopping, assembly of that infuriating furniture, held her hand through the c-section, and held my son. And for six months I was in blissful denial. Then the lost her ever loving mind. I'm not sure what caused it, but home certainly was no longer where the heart was. On top of the fact that an argument, a large check, and a DNA test later, SURPRISE! not a daddy.
Well we separated, and slid into depression for a few months, filed for divorce and so on. She and I haven't even crossed paths in 6 months, she's with some new guy now, and all the happiness to her. My final divorce court date is next week which she isn't even going to show up to. But I digress...
My question is this. A month ago I met a woman who makes me feel like I've never felt. Were almost inseparable. She's a bit younger than me (21) and has a three year old beautiful son. In recent days we accepted and aknowledged our love for one another. Gravy train with biscut wheels right? Oh contrare.
Now I have a whole new problem to face. I have a few of the women from my past (physical aquaintances so to speak) who know I'm with someone now. I've told them repeatedly. But they still make ludicrously strong advances, via phone, email, text, snail mail, and carrier pigeon. I feel like I'm being assaulted on all sides. I've resisted, and ill keep resisting, but it feels like its getting harder.
I know I could probably sleep with one or all of them and get away with it, but that isn't the point. It would be unforgivably wrong, and unfair to her and myself. I love her too much to do it. But I was a cheater and did the wrong things for so long that stopping is like breaking a drug addiction (im just guessing here).
I confide everything to my girlfriend, but I don't feel it would be a good idea to tell her about this. I also am afraid that if I try and go it alone, I'll slip, and do something I shouldn't. Honestly I'm lost. I know I don't deserve the love of this woman, but I want to fight fiercely to keep it. What do I do? HELP!!