It is not a sin to go up for a blessing, although it is unnecessary, as we will all be given a blessing at the end of Mass anyway.
It is most definitely a sin — a mortal sin, in fact — to receive Communion when we are already in the state of mortal sin.
So if those are your only two options, going up for a blessing is definitely preferable.
A lay extraordinary minister cannot give a blessing, so go in the priest’s or deacon’s line if it is practical. Otherwise you’re just “going for a walk.”
Of course, the best solution is to avoid mortal sin (easier said than done, but if we truly love God we should prefer to die rather than commit a single mortal sin). And if in our weakness we do fall, we should go to Confession as soon as possible.
Could you get in the habit of regular (weekly, every other week, etc.) Confession whether you “need” it or not, and if your family asks why tell them that you receive a lot of grace from the sacrament and it helps you stay close to God? (They don’t have to know whether you committed a mortal sin or not; that’s a private matter between you and God and your priest-confessor.)
It’s unfortunate that it causes issues with your family. Part of the problem is that our culture has lost the sense of sin, and everyone goes to Communion whether they are in a state of grace or not (which is tragic). If everyone who was not in the state of grace stayed in their pews, your remaining behind would not draw much attention.