Popi You can't say that ur coordinator has sexually harrased you until u have a solid proof. As u mentioned ur project is in the critical path, normally the coordinators and managers will be in a greater pressure and it sometimes reflects with the colleagues (Even though it is not correct). As u have mentioned some times he is ok and other times he is not. I think this is because of the work pressure.

I suggest the following

1) if there is any mistake from your side (Try to find this out from a third party's point of view) try to correct it.

2) Inform your coordinator politely this kind of attitude will affect the work as well as the environment.

3) Still the same problem exists gather solid proof (Like the SMS he sent to u) and report to the management.

Best of Luck.