For an adult, ‘honoring’ your parents is, in the original biblical languages, largely a financial term. You ‘honor’ your parents by recognizing that they did raise you, and putting yourself in a position in which you can assist them in their old age, or if they become disabled and not able to work.
You ARE honoring them, in preparing for your master’s thesis, and in planning a marriage with a man who will be responsible, too (But, I hope you love each other, too)!
So, you are doing as the church commands, in placing yourself in a position in which you can help them in financially trying times-if and when they come up! Personally, I’d distance myself from them right now. If their behavior is encroaching, in any way, upon your thesis preparation, (it may sound like a loophole-but it is what is expected of you)-tell them you won’t take sides, and request that they stop with any emails written especially to ‘guilt’ you. If they ask why, tell them you want to be in a position to ‘honor’ them…when they truly need it…from you, as a responsible adult daughter.
Do not respond to such emails, if it’s obvious they are trying to get an emotional reaction. If they persist, try and get your fiance or a trusted friend, or even a ‘neutral’ relative (if one can be found) to pre-read the emails for you then, you can simply delete them, once you are assured that they contain no important information.
It sounds as if you have a very bright future, with marriage and career. But, as with most good things, they must be worked on, and nurtured. Whether they know it or not, they are dangerously close to sabotaging your future.
Please-don’t allow them to do this; you’re an adult, and in the middle of making plans to help you be a more joyful, productive, and responsible adult, Don’t let them ruin this for you. You have worked hard for the prosperous, happy, and generally bright future you are planning. Please-don’t let anyone ruin this for you.