(wall of text incoming, sorry :/ )

background: me- I'm 21yr old, male weighing at 261 pounds(118kg), overweight for the better part of my life and this is my 1st serious relationship

her- 20yr old, bodacious, has had nearly 5-7 'non-platonic-non-serious' relationships (at least according to her), and the one with me being the 1st serious one, at least according to her. 8(6.9)/10

now I'm a big guy, I won't hide that, and this leads to allot more insecurity than most guys deal with since mine are on open display, so getting a girl like that isn't something that happens to guys like me that often

So our 'relationship' is abt 2 months old now, however we've been very close friends (almost more than friends) for almost 2+ yrs. I discovered she's had a lot of previous relationships before me, including one where marriage was on the cards before he passed away in a car accident. She tells me shes over it, but sometimes i get the feel its far from that So all this has made me insecure as I really like her, and hence I always felt she was just using me as some kinda bodyguard, so as a result I've been a total asshole to her on multiple occasion, plus being high all the time just made it worse. and thus she too decided to just be mean to me on multiple occasions too and I deserve that, I get it.

So to fast forward we've been bf-gf for 2 months now and again I kinda feel she's just doing this to have me around as a bodyguard till college gets over, since we have majority of the classes together too.

The thing is I don't want to leave this. I feel I won't get anyone else seeing how fat I am, and in my country relationships are hard to come by especially for a guy like me. Now to be fair I have been working out and I've even lost about 10kg (22 pounds) too, But I don't know, I don't want to go through all this emotional turbulence again, and I wanna make this work.

Another thing is, she's very secretive of her cell, like super-secretive, I literally never get to touch it and it makes me wonder if she's cheating on me with any of her ex's this has simply driven me insane.

I wanna make this work, and I'm scared if I don't then this will be the last relationship I ever have. but I don't want to be with a cheat either.

Help me redpill I don't know what to do.

TL;dr: I feel I'm being used as a bodyguard and she maybe cheating on me too, going insane.