O beni herhalde sevmiş! Oysa ben onu her halde sevmiştim

He/she probably loved me! However, I certainly loved him/her.

 It´s a play on words. Herhalde means probably

Her halde means in every circumstance or in every state they were in

The second sentence could therefore be translated:

However I love him/her in every circumstance.

But you lose the pun in English