As far as Barnabas telling Angelique he loved her, no, I don't see that as ridiculous in any way. I, for one, always believed he did love her, and not Josette. He talked himself into thinking he loved Josette because that marriage made sense for him in the social position he was in. In 1795, we have Joshua and Andre discussing how the marriage of their two children is going to benefit both families financially. Also during that time, we have Barnabas visiting Angelique in her room and becoming embroiled in a passionate kiss. To me, that said he couldn't stay away from her, and it wasn't just sexual. His denials, too, were so unconvincing. Thus, when he finally tells Angelique it was she he always loved, well, it made perfect sense to me. What was maddening, though, was what took him so darn long!
Another thing to consider is, no matter what jam Barnabas found himself in, he always had to turn to Angelique for help. Sure, she extracted or demanded a price for it, but the way I see it, she deserved to be repaid!