Please search literature and standard Ic's: look for "High Side Driver" circuits and adapt one of your liking to your needs. High side drivers are commonly encountered in power supply applications to switch loads close to high rail away from gnd. Since you already have 2.5V supply you will not need to provide HV with a charge pump circuit so that your circuit would be a simpler one than a high side driver circuit without a high voltage rail having a charge pump. Good luck!
If you try to use an opamp than you will have BW problem. It could be overcome but you need to employ different techniques than a single opamp to do it. High side drivers are your best bet.