Sticking my oar in again, sorry
I think the OP is feeling very angry at the consultant because s/he thought that they had a 'special' relationship and now that things have changed between them the consultant has cooled their friendship. The OP is obviously in a bad place emotionally at the moment too, because s/he feels 'out of control' with their weight and diet, and I am sure most of us here can totally relate to that feeling.
Both parties are feeling aggrieved, hurt and angry with each other, but for different reasons. The OP obviously enjoys going to the group and feels that they want to go on attending, but at the same time does not have their head in the right place to be losing weight. The consultant feels that the OP is taking advantage of the group to avoid paying the fees whilst s/he is not able to lose the weight. This may or may not be the case, however, what is obvious is that
here is a SW member who has lost their way and really needs help and support. SW is a business and consultants are human, but at the end of the day here is a person who has been doing really well and has now gone off the rails and is in a bad place.
In my opinion, the 'rights and wrongs' of who is at fault really ought to take a back seat whilst this member tries to get back on track. Whilst I can understand that the consultant may not be very happy with the OP on a personal basis, they are the 'professional' in this situation and instead of acting in a cool way towards a former 'friend' they should now be talking to each other and formulating a way forward for the OP.
Unfortunately it is more difficult for any of us, members or consultants, to think clearly and rationally when we are feeling angry, hurt and upset. I hope that the OP and the consultant do manage to overcome their feelings of alienation and manage to sit down and discuss the way forward in a calm and professional manner. Whatever solution they arrive at should be mutual. If they cannot do this together then the OP probably ought to cut his/her losses, move to a different group and start again as a new member with a completely clean slate.
Just my personal opinion