Overstaying in holland?

i got a problem and it really stresses me out..hope to find some advice here..my situation is i am Au-pair here in netherlands and i met my boyfriend here and decided to live with him..we applied for partner visa after i ended with my au pair visa the IND gave me 6 months extension until they give me the result of the our partner visa....first i got denied so we p letter of objection... on march 16 i received the second result which was denied again..so i decided to go back to my own country which is in asia..my problem is..because of stress and dissapointment it caused us to booked a wrong flight for me it is on april 18 which is a none refundable and changes is not permitted.because we want to be together as long as my pport is valid..we forgot about the letter..the IND states on the letter that i must leaVE netherlands 28 days the moment i recieved their letter...we forgot all about this rule..we based so much on my pport which was the validity date is on april 20...meaning i must leave netherlands already on april 13 which was my 28 days.. my question is..shall they banned me because of this? and i will be flying from frankfurt,germany as my origin..will they find it out? so sad that it needs a lot of requirements to be with the one you love..is the love not enough? we just want to be happy but now it will be ended as long distance relationship...thank you for reading... your advise will be much more ppreciated..