How 2 calm a horse & gain it's trust? what should i feed her? & how can she trust? Her ex-name's hellbitch

i've rescued a tb! named her star cos she's a lucky star! she was a bag of bones when i got her (6 weeks ago) but is slowly putting weight back on, i've been feeding her wheaten chaff, bran or polick? the powder stuff which i either mix with chaff or make a mash,& a little bit of lucern but i'm trying not 2 give her 2 much of that cos i need 2 calm her, she's got a bad injury 2 her back leg, where she got caught in a fence when her ex-owners tried 2 put her 2 a stallion, its about 20cm long & all the way across, but not 2 the bone or any tendons.It was 2 late 2 stitch it by the time i got her so is very proud. she's had tetnis shots, antibiotics& anti-inflammatry's.Now the swelling is down round the knee but still swollen at foot, i apply salt water to try & loosen the dead flesh & yellow lotion twice daily, she won't let me wrap it or touch it, has been badly broken & is very insecure. I need her 2 settle & trust me enough so i can get to it & her feet which R also bad. Please Help