Sorry you are here buddy but it is the best place you can be. Step one is to ask her to leave the master bedroom. If she will not leave, remove her things for her. The MB is a symbol of marriage and cheaters do not belong in it.
Step two. Read up on boundaries. Before you try to set any come to the board and run them by us first. Newbies get really confused on boundaries and when not implemented properly they can actually make things worse.
Step three. Exercise, eat healthy, get sleep, meditate and get out and get a life. Meet up with old friends, family, volunteer, learn an instrument.
One way another if you put in the work you will survive and thrive either way.
