Should I take my ex back after she hooked up with someone?

Give the girl a break. If she loves you and you love her don't let one mistake destroy a good relationship. You can't make your whole life a reaction to the bad things that happen to you. Let your life be about the good and happy things. Otherwise you will end up alone. Women are giddy creatures full of love and affection. Women are programmed to be pive and loving and your woman just didn't want to hurt this guys feelings. Its not like she has the pion for him that she has for you. Be happy!