New Horse, older, came with issues

[3cansup]

Hi, im new here, been looking for a forum related to OTTBs. I recently (4 wks ago) aquired an older Tbred mare ,and I was able to figure out her tattoo and found out she's much older than we were told-mare's papers were "lost" yrs ago-and since she's been a pasture pet for the past 4 yrs with a small herd,she's extremely herd bound & forms an immediate serious bond w/any horse she can. She's 19 according to JC, no race record but sire was successful and won . She acts like a 4 yr old,very very high energy, not spooky but extremely anxious and dangerously barn sour. Fine on the trail untill we turn towards home, or back towards the trailer. She knows all her cues,changes leads ect and is a good girl inside the arena but gets so hyped up..she tries to rear and spin and pins her ears ect if I ride her away from any of the other horses. I had her teeth done ( lots of sharp points and cuts on her cheeks), had vet check and got thumbs up; had chiropractic done twice now and she was "out" in 9 areas of her body. She has gained weight and looks great, but she's a nuttcase emotionally. I am starting from the ground w/her, everything done at the walk, since all she wants to do is go faster. I know pretty much nothing about her past since it became apparent that the previous owners were dishonest. She has a large scar/indent across her noseband area and she's very nervous when bitted up and riding (lips flapping,teeth chomp chomp chomping).Panics when put in any type of martingale,feels trapped w/any type of curb chain or noseband. Pulls through everything I put her in.Previous owner had her in a long shanked curb but wich I immed took her out of. I do believe I can form a bond w/her but all my friends think im nuts, "shoulda got a different horse"is all I hear. Is she too old to rehab ? She does try, and riding alone in the ring she's absolutely wonderful.But riding alone is not an option all the time Thanks for listening ..