No, you should not feel guilty at all. The therapist is also part business person, and would not have offered it to you if it either weren't allowed (as if you are in a special clinic) or wasn't doable on the T's part. So no guilt required at all. You'd accept free counseling, say from another organization if it were professional wouldn't you? The cost has nothing to do with your therapy process--other than to alleviate some of your financial burden of trying to take care of yourself, and to give the T an opportunity to tell you your are worth it (finding healing.)